-Has all the power, reliability, etc of the UP2, but is thinner, takes less parts, has a stronger handle, and is much much simpler.
-In the areas where the UP2 was a yellow rod thick, the UP3 is only a white rod thick.
-Also uses no y-connectors or cut parts in this version.
-Can't hold as many elastics as the UP2 (but can still shoot through cardboard with unsharpened gray rods).
I'll make instructions sometime.