www.tinkercad.com
You can design them yourselves in a short time, Tinkercad is almost like working with Lego, and you can learn it in minutes.

Honestly, that's the easy part, getting them printed is not hard either. The hard part you will run into is getting the tolerances dialed in. Because of their size, I would also recommend a resin or powder printer, not a common FDM if you want it to work well and last. If you do go for FDM, you will want these printed on their side, probably for resin as well.

If you are sending them to a place like Shapeways, make several each with different tolerances, the setup and shipping fees will kill you otherwise.

Thanks for the replies!

Unfortunately I lost all of the brackets, so I don't have a lot to work with in terms of building a model. I guess I could measure the mounting holes in the case and try to use photos online to estimate the dimensions, but based on what Leslieann said, it seems like getting it right might require quite a few prototypes.

If I wind up giving it a shot on tinkercad, I'll post how it turned out. Thanks again to both of you for the replies (and the offer to help, Layer_Shift).

 

I'm lucky that I use my right thumb to hit the spacebar, since that's the side the switch lives in. Hitting space anywhere left-of-center often doesn't trigger a keypress unless you really mash the bar.