We're scanning and 3D-printing the world's pollen because

a) pollen is amazing (for some reasons why, see the question/answer below), but

b) it can be really a really difficult topic to communicate effectively.

Pollen grains are microscopic so you can't see them well without a good microscope, and those are delicate and expensive bits of specialist equipment. There are some beautiful images of pollen grains, but even these struggle to fully convey the 3D shapes and variety of the world's pollen. There's nothing quite like holding an accurate, larger-than-life model of a pollen grain in your hand to help you get to grips with it (pun intended).

Why is it spiky? Are the holes real? Why do they all look so different? Being able to touch and hold, turn over and handle a grain of pollen sparks all manner of questions – and with them, all manner of ways to connect with pollen-related science. We want to see more scientists connecting with more audiences in more effective ways about more areas of pollen research, and we're here to try and help make that happen.

Because pollen is amazing! It's beautiful, important, and incredibly useful. Allow me (and a video from the journal Science) to explain...

Pollen grains (and spores) have shells made of one of nature's toughest materials, that we're still only beginning to understand. Those shells have surfaces whose varied patterns have arisen through intricate processes governed by fundamental physics. If pollen hadn't evolved, plants never would have colonised Earth's land surface, and if pollen went away almost all terrestrial ecosystems would collapse. Pollen's movement around the landscape is a critical ecosystem function, and a service to humans worth hundreds of billions of dollars a year just for crops. Pollen is so tough that grains have been found preserved in rocks for hundreds of millions of years, and bogs and lake bottoms the world over hold layers of pollen which tell stories of ecological change over millennia. Pollen grains can help you work out what's in your honey, might help deliver medicines and vaccines, and can even help solve crimes. Plus, of course, they can make you sneeze – they're one of humanity's most significant allergens, affecting hundreds of millions of people, perhaps up to 30% of the world's population.

See? Pollen might be microscopic, but it really is a big deal! This project is all about helping people to appreciate its value more.

For the first phase of the 3D Pollen Project (2018-2020) we used pollen from living or herbarium material that was treated with hot NaOH, sieved and acetolysed, then mounted in 2,2’-thiodiethanol (TDE). TDE is a specialist microscopy mountant with a refractive index (RI) that can be tuned to be identical to immersion oil, an important property when scanning thick, laser-absorbent samples like pollen. More detail can be found on the methods page.

In the project's second phase (2022 onwards), we're going to be trialling a new, much quicker and easier approach, that in essence should mean no special sample preparation at all. This approach involves using a microscope objective lens with immersion correction, which can itself be tuned to work with immersion media whose RIs match silicone oil, glycerol, or water. This should allow us to scan the enormous numbers of pre-existing pollen reference slides in universities and other institutions, without having to recreate or remount them (which would be a task to last a lifetime!). We're trialling this approach with the University of York's Imaging and Cytometry Laboratory in late 2022; stay tuned to our Twitter account and blog to find out if it works! (As far as we can tell, there's no technical reason why it shouldn't, so fingers crossed!)

Firstly, it's important to note that all references to 'pollen' here are a kind of shorthand that includes spores from ferns, mosses and other lower plants. We haven't managed to scan any spores yet, but we hope to!

At the start of the project, the aim was to scan a useful set of pollen grains – thinking particularly of key taxa in north-western European palaeoecology (a bias that came about because it was the material and audience that were most immediately accessible). Some extra taxa that didn't fit this did sneak in, connected to particular aims or requests, but the plan was always to expand beyond this.

As of 2022, the aim is much broader and more comprehensive. We now intend to scan a representative sample of the world's pollen diversity – representative in terms of geography, ecosystems, morphology and phylogeny. The aspiration is that almost anyone, almost anywhere, should be able to find several models that are relevant to them for almost any purpose. It'll take time to get there, but that's the plan! You'll be able to find details of how we're targeting our sampling on the project website by the end of 2022, and there'll be opportunities to tell us about which pollen types are important for you as well.

Generally speaking, our focus so far has been on pollen from extant plants, but we're also very interested in trying to scan much older specimens from earlier geological periods. We're actively exploring whether and how we can do this, so if this is something that interests you and you'd like to try and help, please get in touch!

You can see what's available on the MorphoSource project page, which should (if it's up-to-date...) be broken down in a sensible format on the Available Files page. You can also view a selection of the models interactively on Sketchfab, but not all the files have been uploaded.

To produce our 3D pollen models, we're using a confocal laser scanning microscope (CLSM); all the data we provide is derived from this process.

CLSMs take highly focused cross-section snapshots through the depth of a pollen grain, like a hospital CT scan. At time of writing (October 2022), these laser cross-section images are available from MorphoSource for some of the taxa that were scanned in the early part of the project (2018-2020), and they will be provided for all of them soon in .avi video format and as zipped folders of .tif images.

Image analysis software can turn CLSM scans into models (or 'meshes') of pollen grains' surfaces, by converting the pictures into binary/black-and-white impressions of solid or void. (These meshes include some internal structures, too.) Surface meshes are provided in .stl format, and when 3D-printed as downloaded, with units as mm, they are 2,500x life size.

It is possible to use a CLSM like a light microscope and take standard photograph-like images, though this was not done in the first phase of the project. In the second phase (2022 onwards), we plan to take light micrographs of the taxa – and individual pollen grains – we scan with the CLSM. We hope that these will add value to the dataset, especially when used together with the laser cross-sections and surface files.

In the first phase of the project, typically only one or two representative grains in a sample were scanned – generally ones that 'looked right' or which illustrated important variation in structure (like the different shapes of hydrated and dehydrated grains). This was predominantly dictated by resource constraints – time and money for using the CLSM, and the relatively sample-poor slides which were specially prepared for scanning. In the second phase of the project, we hope to produce laser scans and surface models of several grains of each taxon, as well as a larger number of light micrographs. At time of writing, this has still to be started, but indicative numbers might be 2-3 scans and surface models and 10 light-microscope images.

The answer to this depends on exactly how you're asking the question...

If you mean 'is it possible to scan/make 3D models of X?', then you might find some answers on our '3D Not-Pollen' page. This provides a guide to key principles for whether and how different microscopic, (mostly) biological things can be scanned for 3D-printing, as well as links to resources other people have previously produced. As the project's name suggests, pollen (loosely defined, to include things like spores) really is our main focus, but we would also love to help expand the microscopic worlds people can enjoy through microscopy and 3D-printing. So, if you need a bit more information than that page and its resources can provide, or if you want to discuss things in more detail, do feel free to get in touch.

If you mean 'can you scan/make 3D models of my favourite pollen?', then the answer is 'maybe'. In the first phase of the project (2018-2020) I was very happy to receive samples of pollen to try and scan, but the time required to remount these meant that I managed very few with the limited time and funds I had available. In the project's second phase (2022 onwards), some technical tweaks should make scanning much quicker and easier (and resources are now, happily, much less of a constraint). However, we're also aiming to move away from adding taxa to the collection opportunistically, and toward a targeted sampling approach that efficiently and effectively covers different elements of global pollen diversity. Details of how we're going to do this – and how you can ensure we know about your key pollen types – will be available from late 2022. If you want to know more in the meantime, please get in touch.

Yes! Scans and printable surface files for all scanned taxa are available for free on MorphoSource: see this link. You need to register for a free account to download the files, but there is no cost.

Yes, but only a couple of small ones. The files are on MorphoSource under a CC-BY-NC 4.0 (Creative Commons attribution non-commercial) licence. This means you can use the files free of charge provided your use is not commercial, and provided you give appropriate credit to ‘Oliver Wilson and the 3D Pollen Project’ when you use them. The only other requirement is that you inform us about how you use the files – a quick email or tweet, or a comment when downloading from MorphoSource, would do. This is important because it helps with reporting to funders and other interested parties, and because it’s great to know how they’re being used!

Can you print some of the models? Absolutely! Can I print them for you? I’m afraid not. I don’t have access to my own printer, so I’d just be doing the same as you – finding someone else to do the printing. There are a number of ways to get this done, and it needn’t be difficult.

Many universities, colleges and schools have 3D printers of their own (often in engineering or product design departments), and some have dedicated makerspaces where 3D printers can be used at very low cost. Libraries often host makerspaces, a UK-specific list of which can be found here. Otherwise, there’s a vast range of commercial 3D-printing services available – but be aware that prices can vary enormously. One way of looking at the available options is through a site like 3Dhubs, which compares a lot of different companies and has a huge variety of options, but I’ve used 3D Tomorrow, who I’ve found to offer a good range of high-quality services at very low prices.

The range of options for 3D-printing a model can seem overwhelming, so, while I’m no expert, here are a few general principles. Bigger prints cost more – simply because they use more material – so if you want to save a bit, scale the files down. However, you can use cheaper printing technology on larger models than smaller ones, so there’s a compromise to be made.

Fused filament (FFF/FDM) printing is cheap and widespread, but not very good for fine details or complex shapes. I’ve used it to print full-size (2,500x-scale; left-hand photo) models of my pollen and it’s worked well, but it wouldn’t be appropriate for smaller sizes. Stereolithography (SLA) is very good at these fine or complex shapes – I’ve used it to produce models as small as 500x scale (fingertip size; right-hand photo) which came out very well – but it’s more expensive, and for full-size models the cost may be prohibitive.

Other printing technologies are available, but these two are the most common. If you have more detailed questions about printing the models then by all means get in touch and ask, but you may be better off having the discussion with whoever’s doing your printing.

That depends on how you scale them. The models online, if their units are treated as millimetres, are 2,500x life size – all to scale with each other. This means that full-size models of the pollen in phase one of the project range from about 4cm across (Filipendula ulmaria) to 19cm long (Pinus sp.); some of the phase two models like the Cedrus species are larger still. The scales aren't set in stone, though, and you can make them larger or smaller to suit your needs. There’s also nothing to stop you from printing models at different scales so they all end up a similar size, though it would mean that you can't use them to compare the pollen grains' real sizes. You can preview a model’s dimensions at different scales by uploading them to the print services at 3Dhubs or 3D Tomorrow.

It's (almost*) entirely up to you! People have put them on display in natural history exhibitions, used them to talk about bio-inspired design with school children, waved them at people to spark conversations about hayfever, hidden them in tubes of soil or bottles of fake honey, used them to decorate birthday cakes, given them away at conferences, used them to illustrate important teaching points, dressed up like a bee and walked around a botanic garden collecting them... The microscopic world of pollen is your oyster!

If you're on Twitter, the 3D Pollen Project's liked posts contain a wealth of examples of how the models have been used so far, including most of the ones listed above. If you're still a bit stuck, or would appreciate more guidance, you might like to look at our Outreach Activity Guide, which has detailed plans for three complementary pollen-themed activities, two of which use 3D pollen models.

*The files are shared under a CC-BY-NC 4.0 licence, which means commercial use is not permitted.