My son is 10 and has just gotten into the wonderful world of paintball. He didn't like my mags or autocockers, so I took him out to our local field and let him play with a bunch of different style markers. The spyders were his favorite (but we're definitely not going there) so now he has his own Azodin Kaos, built up nice and tight just for him out of spare parts.
AA vigilante reg
ANS drop with drop kick and on/off
a felt pad as a travel stop for the trigger (I'll be working on this more when I have the time. He said he didn't want the single trigger.)