@sabbatical per Wikipedia, it's made of plexiglass, so you can just get a tin of acetone from the hardware store. That's good news; some plastics require nastier or harder-to-source solvents.

@khird plexiglass! hm well then i wonder if that’ll work for the CRT monitor base which is also cracked. wonder if it would be a strong enough mend for the weight

@sabbatical Worth a shot. Looking at the picture I think the fracture will mostly be under compressive stress when the computer's upright; that is to say, the weight of the machine will tend to press the two faces of each fracture together rather than pulling them apart. Can't say from that pic whether that looks to be true of the monitor as well.

It might not be invisible but I'd guess it'd be structurally adequate.

@khird the monitor base is just one clean break (unlike the shattered cube casing) but it does look like maybe a spot with multidirectional force. this post suggests it’s made of polycarbonate: https://www.applefritter.com/node/5273

@sabbatical Wikipedia says acrylic, not polycarbonate - and I tend to think that's likelier, just because it's a quarter century old and it looks way too clean for lexan (look at how hazy old Nalgene bottles etc. get), plus lexan is notably shatter-resistant, and the evidence suggests that's not true of the article you have.

If it is lexan, you probably need something more exotic like dichloromethane, which both is harder to source and demands MUCH more attention to safe practices regarding inhalation, skin contact, etc.

@khird ah, i do recall folks selling replacement bases on ebay were calling them acrylic. overall it is pretty strong stuff — the way the base got the break in it was because a bunch of boxes were inadvertently piled on top and put a ton of extra weight on the already-heavy monitor, so likely wouldnt have happened normally. i'll try to remember to take a photo so you can see the way it broke.

@khird how do you know so much about what works with what, btw? very cool, i’d love to have this sort of in-depth knowledge on physical properties of things and what works well for what

@khird here’s the break in the base

@sabbatical Hm yeah that looks to be in shear if I understand the orientation correctly. You can still try solvent welding it but you might benefit from coming up with a way to clamp things firmly in place while the weld sets.

@khird yep, the monitor is on its side. ok thanks! acrylic + shear means i should prob look for something like tensol 70, eh? https://cutlasercut.com/drawing-resources/expert-tips/bonding-acrylic/

@sabbatical That sounds like an epoxy - they want you to mix two components and apply with a syringe. The point of a solvent weld is that it just dissolves a bit of plastic from each face, creating a thin layer of liquid plastic-in-solvent solution between the two pieces, and then as the solvent evaporates, the plastic remains, leaving it as one continuous piece. Were I in your shoes, I'd just get a can of acetone from the local Rona/Lowes/Home Depot and give that a shot - but your dollar, your decision.

No matter what you use, you'll have to get the two faces lined up as exactly as you can to maximize the surface area in contact (viscous products are more forgiving in this regard, but you have two perfectly mated halves of the fracture, so that's probably more hassle than it's worth). Then you'll need to clamp them together without flexing the join. I think the clamping will be the hard part, because it's a curved surface without anything to easily line them up against.

@khird wait, is this what you're suggesting for both the plexiglass cube base and acrylic monitor base, or just one of them?

@sabbatical Plexiglass is a trademark for acrylic - it's the same thing!

Polycarbonate's a different thing, but I think the forum post that made that claim is wrong.

@khird oh wow, no way! well the more you know! the cube base does seem like a much more rigid material than the flexible monitor base, but now that i know plexiglass IS acrylic it makes sense they’d just use tweaked formulations of the same thing if they could. they do seem well matched in terms of clarity, sheen, etc.

@khird also, i think i have been conflating plexiglass and fibreglass in my head

@sabbatical Understandable! I suppose it would be possible to make something that was both - glass fibres embedded in acrylic. But that’s not common to my knowledge - plexiglass doesn’t usually have embedded glass fibres, and fibreglass usually uses a different plastic in which to embed them.

@sabbatical Thanks! I'm the son of two chemists, and I broke my fair share of plastic toys as a kid. My dad would use the repairs as an opportunity to teach me.

@khird very cool! wonder if anyone’s written a laypersons guide to this stuff. maybe you should! :) not wanting to use the wrong stuff on the wrong stuff is a huge barrier to tackling tasks like this usually — for me and for many others, i’m sure. for good reason, it seems!