Adjustable height mini platform

I made a few changes to the "[Mini Jack Stand](https://www.thingiverse.com/thing:1857597)" for use in my Dungeons and Dragons game. These platforms allow for 3D battles to be represented with miniatures by adjusting their height easily on the battle map. I'm using them for underwater fights; they'll work for air battles too. Or non-gaming stuff, whatever!

I swapped out the cradle at the top for a 25mm square platform, added two sizes of extender beam and a sleeve for even more height (you can add as many as you like, though it gets wobbly with more than one extension), and shrunk the whole thing a bit in order to use pieces of a [bamboo BBQ skewer](https://www.amazon.com/Fox-Run-Bamboo-Skewers-Set/dp/B000UJ0Z10) as a pin rather than a screw.

The original design is mostly preserved, and it's great. The holes in the inner and outer pieces are slightly different distances apart, which lets you match different holes together for very precise height levels (a bit like a Vernier Calipe