Wax 'em

These fins are the first of their kind, being 3D printed yet strong enough to shred on. The only thing needed after a print is to give them a smooth surface, and it turns out surf wax matched to your local water temp is the perfect stuff.

1) Put on some disposable gloves, get your surf wax and something to cut chunks off for filling in corners.
2) Cover the fins and wings in wax. Go over the surfaces with your fingers to rub the wax into the surface, forming a smooth skin on the fins.
3) Use small bits of surf wax and run them across any corners to fill in / smooth out the hard to reach areas.

Wax is hydrophobic (repels water), this makes for lower friction and higher speeds.

No Sharp Edges

Sand down any sharp edges. I do this before sending fins out, but I may miss a spot occasionally. Round edges makes them safer, being 3D printed they'll still break away if you land on them. Treated with care the fins should last for years.