I borrowed some XDA keycaps from a friend and cast moulds around them. Now that I have some polyurethane resin I should hopefully be able to try casting some caps tomorrow! Or maybe later in the week.

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My first run of keycap casting was a partial success, partial failure. I forgot my pointy tool to get the air out of the keycap stems so there was a big bubble instead of a stem. Other than that they formed really nicely! Some very minimal bubbles on the outer edge of the top but the form and texture look great.

Second attempt at polyurethane casting was a success! The keys are fully formed and the outsides have no bubbles.

They even fit fine on my keyboard, although one is a little looser than the other. It's clear that this resin isn't black, just a dark grey.

The working time of about 7 minutes turns out to be accurate, which is about right for the 4 moulds I have. They seemed to need the full 1 hour cure time, at the minimum demould time of 30 minutes they were a bit too flexible.

Well that's a dead mould, and the last keycap didn't survive either :(

The silicone gets brittle over time. Depending on the mould, people say you can get anywhere between 10 and 120 casts from it (for something with features this small it'll be on the low end). It looks like this one only managed somewhere around 16 :(

Basically, casting an entire keyboard worth of caps is a bad idea. But I'm doing it anyway!

The full keyboard is getting there though! Some of the caps are a little loose so I had to put some tape underneath. It makes the fit of the stem a little tighter (hopefully without breaking the stem)

It's very tedious with only two moulds, and I'm out of silicone to make more. This is definitely making me want to get a resin 3D printer to make some custom shaped ones.

@gbrnt for something cast in lego bricks, they definitely look professional!

@piggo Thanks! I think the vents could do with a bit of work to get rid of the bubbles. Or I could sort out a vacuum chamber or a pressure chamber, so there are less bubbles in the first place.

Generally I'm surprised this is turning out so well with minimal effort. Casting is pretty cool!

@gbrnt @piggo I casted Warhammer miniatures (I have a past as a miniature sculptor) in lego bricks in the past. It's one of the best methods. :D

@nuala hehehe my partner keeps trying to eat them too. Maybe I should get some brown resin and make a chocolate bar keyboard?

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