I usually do spin top mods, but here is a yoyo mod I did recently.
Saber Wings have 3 problems; they are too light, the rims are too sharp, and they are transaxles. I cut a hole in the cap so I could put in rubber weight rings, rounded out the rims to make them softer and put in a bearing from an old Raider. I had to sand the spacers for half an hour to get the gap thin enough for descent responsive play. I have plenty of unresponsive yoyos that play well but only a few responsive ones that are fun to play with… This is one of them