Ultimately there wasn't really a lot of "customizing" involved. I had to buy each one of the pieces for him. The fun in that came from cruising eBay and another online store Opstoys, for the right parts.
I then waited until I had all of them to put everything together. It was fun deciding what weapon, LBE/LBV equipment, comm gear, and other such stuff. I think the next one will be either a Special Forces soldier or maybe a CCT/TACP airman. I've also thought about doing another USAF Security Forces airman, but base this one in the US in cop gear. So many things to think about.