Here is my print of a kid-size proton pack and wand. The size is 70% and fits for my 4 year old son.
The parts fit nicely tougether; some parts are realy small due to the down-size. I used 2 component glue and filler to combine the parts. I glued all the parts to one pice and added angles to screw the hole proton-pack to the backplate. I did not put any electronics in it, but as I can remove the pack from the backplate it can be done later. At the cyclotoon, battery graph, wand graph I only glued colored cardboard from the back.
I also skiped some parts of the wand to make it easyer to carry for my little son.
Verbatim 1,75 ABS