Here's a project that I have been working on for about a year. That sounds like a lot, but I only worked on it for a few minutes here, a few there. I think the total actual time was probably more like 20 hours.
Anyway, here's the process.
It all started when a neighbor was throwing away a perfectly good globe that only had a collapsed southern hemisphere. I looked at the northern hemisphere and, naturally, the first thing I thought was "Hey, that looks like R2-D2's head!"
The next thing I did was find a few good pictures of R2-D2 for reference. The diameter of the globe is 12", so with that measurement, I brought the images into Illustrator, tossed on a grid, sized the images so the diameter was 12 units and, ta da! I could now figure out the correct dimensions of everything else. I drew up a few schematics and moved on to construction.
First, I needed materials. I searched for 12" diameter cylinders for a few weeks. I considered 5 gal buckets, but they were not exactly the right size and they had a bunch of extra plastic around the top. I looked at plastic garbage cans, but they almost always tapered a bit. Finally, I thought of a sonotube. It's a cardboard tube used for making concrete pillars. We used one when we built the Thanksgiving Point water tower on the Lehi pioneer-days float 7 years ago. A quick visit to Home Depot, and I had a 12" diameter cardboard cylinder. It was 4 feet long, and I only needed 15", so I cut it down to size. Incidentally, if anyone has any cool ideas of what I can use the remaining tube for, let me know. It's now in 2 pieces.
For the legs I chose my best friend, foamboard. 3/4 inch. I also cut some circles and glued them into the tube and the dome for extra support. I used a poster mailing tube for his neck.
With help from the R2-D2 builder's group online, I got a template of R2's skin. I scaled it down and simplified it a bit.
I covered the cylinder with white poster board and struggled with what to use for the outer skin. I considered more poster board, but it was so thin that you really couldn't see the depth. I tried styrene plastic (1/16"). This stuff is amazing, and I will use it in future projects for sure. The cool thing about it is that first, you can cut it with an exacto knife (straight cuts just require a simple score and break), and second, you can heat it up with a hot air gun (or oven) and it becomes pliable, within seconds it hardens into the new shape. I actually covered the back half with it and cut out all the shapes. In the end I decided that it wasn't going to work. Although straight cuts are easy, if they are on the interior surface, you can't easily snap them off so you have to make a zillion cuts. I ripped off the plastic and went with craft foam.
The sheets are smaller than I needed, so I had to piece together 4 sheets to cover him. But talk about easy. I was able to glue it down with elmers glue and cut out all the pieces in just a couple of hours (compared to about 4 hours on one side - and needing to use super glue, with the styrene).
As for the details on the body, I built them out of foamboard and styrene plastic. For his face, I used parts from old camera lenses, video cameras, water bottles, and plastic Easter eggs. The feet are also constructed out of foamboard but I used 3" tires from a big RC Mercades and wire hangers for the axles.
Then I spray painted the head silver and the body and legs glossy white (the foam stood up just fine, though it didn't get very glossy). Next I hand painted the metallic blue and a bit of silver where needed. I connected his legs to the body using toilet paper tubes.
True fans may notice that he isn't actually 100% finished. He's missing the battery packs on his inner feet with cable connecting into the foot. I will be using several toilet paper tubes for those, so I'm waiting for the inventory. Once I got him this complete though, Val wanted him out of the house, so he lives in my office at work. For now he sits on my couch, but I have the idea brewing of building him a proper "place". Maybe a simple pedestal, or maybe the top of an X-wing fighter - wait why not a full sized X-Wing fighter! Well, no hurry, the idea will come eventually.
Oh, And he made it to work in time for Halloween, so here he is in costume.