I recently tried a couple different methods and ended up nearly shredding my flak vest in the process.
First i tried just the velcro. After washing and dying my vest to get the color right (still not happy with it...too yellowish) the velcro started coming off. I used 2 ton epoxy on the velcro and slapped it on the armor. The epoxy wouldnt adhere to the velcro strips, so they ripped right off the armor. I ended up using JB Weld to keep the velcro on the armor.
I then tried snaps. I bought the snap kit (the one with the 2 piece snaps, the little platform and punch). I ended up either making the hole too big and the snap wouldnt stay or the snap wouldnt stick to the armor. I scrapped the snaps because I couldnt get them to work.
I then went with the Boba Maker tutorial and used bolts. I bought a bunch of eyelets and poked holes all over the vest. I used construction adhesive and glued the bolts to the armor. I screwed up a bunch of the eyelets and made the holes too big, so I had to sew them in place.
Overall, I determined I can't sew or do anything fabric related.