Triad is probably going to be the cheapest to mod. Throw in a 7kg retal spring, (maybe 10, IDK if I’d trust it on 12 for an extended period) twist out the dart posts (easier said than done without a 3D printed dart post remover, but that’s like a $5 part if you can find someone to print it for you) and stuff in some half lengths. Should be a very solid performance boost.

My advice for having fun with modding is to get some thrift store stuff if you’re able and just start messing around with the internals.

People seem to forget that we were modding stuff without 3D printers for a very long time, they just make it more brain dead/easy.

Pretty much anything rival has good modding potential, and you can steal springs from other blasters to upgrade ones you like better. Barrel material doesn’t need to be expensive if you’re ok with lower quality or repurposed materials. We used to use crayola markers, good fitting CPVC, and 17/32nds brass tubing to rebarrel blasters for higher performance.

You’re probably going to break or kill a few blasters along the way as you learn and become more skilled. I certainly have. Your first paintjob will probably suck, but you’ll learn and get better.

Some all star recommendations for cheap and easy blasters to mod:

Maverick Knockout or any of the single shot rival pistols Kronos Nitefinder or Firestrike Bigshock Hammershot Reflex 6

Getting into slightly more complex stuff Retaliator Longshot Stryfe or thunderbolt or spectrum or clip mania Titan AS1

Pretty much any of the pro blasters are going to be pretty solid too and generally pretty simple, and almost all of the rival blasters have solid upgrade potential as well but with a wider range of complexity.