I understand some of these words individually.

Two of these objects are chess boards

I had to reread that like four times.

r/ihadastroke

This is cool and not that complicated!

For current resin 3d printers you have a vat with resin, a platform that lowers into that vat, and a UV light source below the vat to expose the resin.

For this, they added a second vat that can move relative to the platform and UV light source. So you can swap out materials by moving this platform with two different vats on it.

BUT resin is thick and sticks to the print. So if you're switching material you need to get the old resin off otherwise you'll mess up your print and contaminate the resins. So they added a motor to the platform to spin the old resin off between material switches.

Sounds messy, but it's a cool way to get multi-material resin prints.

Using a Flux Capacitor? Asking for a friend…

Sounds like every print would take several hours longer

I mean, considering there was no practical way to make this kind of print before, I think a slightly longer print time is a fine compromise.

Great summary!