This is a replacement insert for your standard tape dispenser that can print with no supports. There are lots of these on Thingiverse, but I couldn't find one that could be printed without support on the Makerbot in my classroom. I designed this one in two-pieces, so they each print beautifully with no support, and can be easily assembled.
Tip: print the axle rod on it's side, so that the grain of the filament goes lengthwise; this gives it strength in the direction you need it. You may need a rubber mallet to tap the rod into the hole of the insert.