Free: Contests & Raffles.
Get some nail polish and fill in the letters or number on the receiver give each person a different color . It looks cool too .
I'm not sure what you got, that would dictate what bling you could put on. I seen in another thread you might have went with DPMS oracle's??That lower is pretty much a blank canvas, have them engraved? http://vadertactical.com/engraving-gallery/strip them down and have everyone cerakote their own lowers? engrave AND cerakote? matches your car
put some stickers on them