[dejv]

Not sure about availability around the world, but I would say Merkur: https://en.m.wikipedia.org/wiki/Merkur_(toy)

Fun fact: first line for creating contact lenses was build using this system.

[kk_cz]

Here seems to be a catalog of their current sets: https://indd.adobe.com/view/1881b5e5-34ee-4e7c-8b19-2f25b314...

They have en e-shop (although quite poorly translated) and it looks like they are shipping within EU to US and to some other countries: https://eshop.merkurtoys.cz/

(I am not affiliated just used to like these things as a kid)