What you are looking at here are bases for paper miniatures.
If you are into tabletop roleplaying (like Dungeons & Dragons, but including so much more) you might have run into paper miniatures before. They are cheap, replaceable and take up little space. If you are looking for examples, check out Trash Mob Minis and Printable Heroes (no affiliation, just awesome stuff).
Why am I telling you this? Generally, these minis come with paper bases. They work fine, but I decided to make printed bases that I can reuse for any minis I want. They are pretty flat, and allow the minis to be stored flat as well (I recommend card sleeve binder pages).
You can find bases for medium (and smaller) minis as well as for large ones. I did not create any larger ones because in my experience there are few paper minis that are larger, and if you are going to use them I hope that you can improvise with the bases in here.
does not matter I used PLA, but anything goes.
any you want; you can use different colors to distinguish similar-looking miniatures for easy reference.
This is a very simple model. If you are running into unforeseen problems let me know!
Also, you probably should not not scale this! The gap is set to work with minis made up of two layers of cardstock. Scaling it will give you larger bases that will not hold minis properly.
Thoughts behind the design
At first, I wanted to design a slot with a slight curve to it, thinking that it would hold minis no matter their thickness (in certain margins).
Test prints did not work as I had hoped, though, because they never gripped a mini tight enough for me to lift it up without losing the base.
So I eventually ended up with this "toothy" design. The idea behind this was that it would act like a lot of bends to put the mini through.
If there is a way to make the bent slot idea work I have not found it yet.