I've been a member of the Austin Hackerspace (http://atxhs.org) for a while, and it's paid dividends in saved expense on tools. Plus the community of experts it has attracted has allowed me to quickly finish projects that would take months of research on my own.

Renting has the additional advantage that you're not stuck with the particular technology that you bought. If two jobs benefit from 2 printing technologies, you can have both.

On the other hand, a benefit of having your own proto shop is that if you're skilled, you can prototype and modify quicker than you can specify. And don't overlook ancient methods. You can still do a lot with woodworking tools.

When you work wood with metal tools you're going to have do a very thorough cleaning job afterwards because the acids in wood will wreck equipment quickly.

Thanks for the warning. I hadn't realized this problem exists.

I'd argue that additive manufacturing via hobbyist FDM printing is a lot cheaper for one off designs than subtractive manufacturing of any form, because the consumable cost is limited to utilized filament and a tiny amount of printer maintenance rather than huge amounts of waste combined with expensive, finicky tool bits and the same kinds of maintenance.

I do agree that for items like a Raspberry Pi case which could be mass-produced via molding to much better tolerance at a low cost, 3D printing might be silly, but for truly one-off, low accuracy consumer parts I don't think 3D printing can be beat.

I personally have also not had much problem getting square, true, dimensionally accurate prints with a crappy printer (Solidoodle 2). The most deflection I've ever seen is about .8mm across the 150x150mm build area. That isn't perfect and obviously won't work for precision equipment, but combined with ABS's flexibility and forgiving nature it's certainly good enough to make one-off enclosures, fasteners, buttons and knobs, adapters, and other "glue" parts, which is most of my use for 3D printing.

I will say that 3D printers are hard to set up, and that's probably the source of a lot of the warped cases you've seen. CNC mills and lathes are just as hard to set up, though - you've just generally paid the vendor tons of money to do it for you.

Might be less hassle than renting an actual machine.