I had done enough reading on the Astromech.net web site to know that I was undertaking a big project, and one that might never "end," but I'm beginning to think there's a more sinister aspect of this project I hadn't fully considered.
Building an all-aluminum R2 is expensive. And even if you don't do all-AL, you can rack up a pretty hefty tab. If I source all AL parts exclusively, I'll have $5-6K into this thing before it done, it seems. I already spent $160 on the two little arms that pop out of R2's front (above the vents). The front vents in AL are over $250 from the club member that makes them. The dome has three "holo-projectors" that are $130 each in AL, not including the add-on to make them movable (which doesn't include servos or electronics, just the mechanical parts), so for all three it's upwards of $500. The dome itself with accessories was over $600, and the dome itself is loaded with tricks. Even the electronics and lighting pieces are pricey from the members that build them. It's all understandable--volumes are small, and labor is high for many pieces.
So this week, I've discovered that pretty much every small step I take, if I stick to all AL, can be $250-$500 per step. I can't justify that kind of money, and I have enough confidence in my own abilities that I am pretty sure I can build a great-quality result by choosing carefully what will be AL, and what can be other materials. There are lots of pictures of droids with resin and 3D printed accessory and decorative parts, and with proper finishing, these are indistinguishable from AL.
And as for the electronics, I'm not seeing how most of what's available "off the shelf" will do what I'm imagining, so I'm already thinking I'll roll my own, anyway.
The original R2s were cobbled together from scrounged parts (e.g. the original "holo-projectors" are gimbal lights from an old aircraft). I'm going to keep with tradition.