Bent the fin on my mini mal while I was in Cornwall a couple of weeks ago. I not only snapped the tail fin but pulled out a fin plug too.
In the box of bits that came with the board I found a tube of Solarez - UV curing resin.
The glass round the hole had split in places so I though I'd best fix that first.
Next I got out the Black and Decker Powerfile and filed the fin plug back so it would go into the hole without snagging. I filed a lot of grooves in the plug as well so the resin had something to grip to.
I'd bought a new set of fins to replace the broken one:-
Ready for action this weekend.