The generation I spinner is an easy start. There are three tiny screws on the bottom. This allows the top piece to come off as well as reveals a chunky drop-forged metal piece. It even has a part number on it. I'm not a scrapper and only a fair tinkerer so I'm not sure what kind of metal it is. It isn't magnetic but it's much heavier than I would expect for aluminum. The surface is somewhat dull, but then again it's for weight, not show. The interwebs suggest it could be zinc. At under $1/lb, this 1oz weight would be worth about 6c. No point buying out the entire world stock of Ninjago Spinners for scrapping. It doesn't really taste like a zinc tablet though. Stainless?
The central fig stand was a little harder to figure out. It has a compression clip that goes through a hole in the bottom portion. I chewed the tabs up a little bit before I tried pulling from the top side. A good solid pliers grip on the upright portion, a little twist, and *BAM* my elbow hits the wall. The stand has no part number on it but the ring does.
Piece of cake, let's tackle the second spinner. The design of this one is different. Where the gen. I has a tapered bottom, this is flat with a protrusion only at the pivot point. The attachment method is also different. Instead of mechanical fastening, it's designed to rely on snaps. Ugh, how to pry that apart?
The fig stand can come out first thing. That gives a little more of a sturdy central portion to leverage against. Oh look, this one has a part number on it! Same design and everything. I'll assume it's the same part as the first one.
At first I tried pushing through the bottom holes to release the pressure on the snaps. This didn't work very well. After that I gently pried a flathead jeweler's screwdriver between the two shells and s-l-o-w-l-y used some leverage. There was some plastic cracking but the snap released soon enough. The other two were no easier.
Once these are apart, you can get the metal weight out. This one is a different design but has no part number in it, just a mold position stamp. The ring is a slightly different design from gen. I but still noticeable. The little nubs on the ends are too small to fit in a minifig arm, but too big to be used in any of the expected mini-pin places.
Since Bricklink has not been interested in these types of pieces for their catalog, look for these in the BrickOwl catalog soon!