Hi,
I just saw this thread and thought I'd chime in. I've got a 3d printer at work (Fusion 360) and I've spent sone time learning FreeCAD and Slic3r (I try to stick to OSS when I can).
Anyway, years ago I pulled a Pioneer SA-7500 (?) from the recycle pile. The power switch was burnt out and my ham-fisted attempt at fixing it didn't work. So I just soldered it permanently "on" and it just sat unused for years due to other problems.
Recently, now that I've had some success bringing old things back to life, I had another go at the Pioneer amp. I disassembled the power switch into two halves : the "mechanical" half and the "electrical" half. I threw away the electrical half and replaced it with a little plastic doodad that I 3d printed.
Basically it's just a flat disk with indents so that the metal tabs from the "mechanical half" can bend over and grab it. In the center of the disk is a hole for the mechanical pushrod/plunger/actuator to pass though. And right next to that is a little shelf with mounting holes for a mini snap action switch. Everything worked out so that the pushrod turns the snap action switch on and off. Since the tiny switch can't handle the full current for the amp (neither could the original!) I used a thyristor circuit that I learned about on AK.
Anyway, this was sort of a one-off ad hoc job, but it helped keep an old amp alive. In my opinion, its a perfect "use case" for what 3d printing is actually good for.
Now for some pics.
First, the two halves of the original switch:
View attachment 1423477
Next the doodad I printed and the mini switch:
View attachment 1423480
And finally the whole thing assembled:
View attachment 1423483
In that pic you can see the (brass colored) pushrod pressing the miniswitch shut.
I could have done a better job (made the disk a tad thinner) and been more precise bending the tabs, but I was in a hurry to test it. Then I decided the best thing was to NOT bend those poor little tabs any more!