Oh how the internet keeps making things easier! Now I can get everything I need to make Columbia's collar from Amazon. All I have to do is spray-paint the lock washers gold, and space my rivets out 3/4" apart. Check out these links via my Amazon Associate account -
Honbay 12PCS Rivet Studs (Amazon Assoc. Link)
CRAFTMEMORE 50 White Clear Rhinestone Rivets (Amazon Assoc. Link)
External Tooth Lock Washers (Amazon Assoc. Link)
Milakoo Adjustable Leather Collar (Amazon Assoc. Link)