I got my two sons (now 13 and 14) a collection started a few years back and have been keeping it going at Christmas and
So far, they each have a favorite color (one likes red and the other likes Blue), so I've tried to find knives that come in multiple colors (every now and then we mix it up and change colors).
Got them the Blue/Red Kershaw Skylines, and a set of Scallions (also got them each a Victorinox SAK - one in Blue and the other in Red). They even branched out and one wanted a Buck Parallex while the other wanted a Byrd Robin.
I picked up a Blue Delica and a Black one and then swapped the scales from a Delica trainer to the Black one to come up with this (I usually get one like theirs and mine are typically Orange):
I just recently got them their first outdoorsy/bushcrafty fixed blades and we're headed out this weekend to build a fire and cook on it with a tri-pod/hanger and build a shelter.
Got my 13 year old a Mora Bushcraft (he wanted Orange this time) and my 14 year old a Condor Kephart (and picked up a Becker BK16 while I was ordering):
Good times.