Hi...
I am new here ... I have spent some years trying to mold my own finds ...
and then I found an old thread here ..
www.seabreeze.com.au/forums/Windsurfing/Gps/powerbox-dimensions?page=1
Thank you very much for pushing in the right direction ...
During the corona isolation period I worked on the idea ...
And I've perfected a poverbox that fits perfectly in a fanatic poverbox
The idea is to print a PLA negative shape and try to mold a 20 layer fiberglass fin.
I have attached some pictures of the project so far ... if anyone wants to have .stl files please ask
creation in Fusion360:
first print of test mold:
First test with PUR.
Wouldn't spend a lot of time on fiberglass if it didn't fit ...:
of a quick and raw test cast, the result was actually satisfying:
First test on board ...
Due to PUR, the casting has become a little thick in the middle but otherwise perfect fit
Now there is only one complete form left to print ... and then live testing on the water....
it's going to take some time ... but I'll bring some pictures when the final result is there
Really nice!!
If you allow me, I have some tips for lamination with 3d printed molds:
Save yourself some material and print with thin wall thickness. fill up the "outside" of the mold with plaster and then use silicone to glue it to a wooden board. This will make a really strong mold that will evenly distribute the clamping pressure
For the mold surface:
apply a thin layer of aluminium putty and sand until you can see the plastic, finish with 1000 grit. Some release agents, as well as resins, can react with the plastic and result in poor release and ugly surfaces. The aluminium putty prevents this and makes it so you can reuse your mold a few more times before it's done for
high Five to you and respect to anyone that gives it a go to make their own kit 
theirs something special about cracking a fin out the mold it's better than Xmas! Never gets tiring...that said the heart can sink when u realise what s*** you have just made but when you plug away and it pops out perfect it's special 
