just finished this new fin. After all the talk on modifying fins i thought i would post some pics.
This fin started life as a 38cm Caveman Goldwing Pointer (powerbox). I got it cheap 2nd hand in the by and sell.
My first mod was to rebox it as a tuttle for my slalom boards. It went ok but didn't feel any different to the 36F2 stock fin.
My next and hopefully the lasdt mod was to take the drop saw to it an make a nice slick 28cm weedy at 40deg. I have been meaning to box the fin a bit further for a while but i had never bothered.
I hope to give it a try tomorrow. I plan to use it in my CA SL52 and CA SP50.
second hand fins are going through the roof!! 
looks real good i'll get there one day small steps
I do like the way its set forward .. even with the Ka fins i didn't like gybing with them i don't know what it is... but i suspect its because there so raked back .. it feels like u have a rudder on
hope it works for ya please post results ... good work !
Cheers mate! I have got one of those custom maui fins like the one you cut down.
Hmmm the posibilities
your 40cm is also coming on. I sanded the base back at the fin center line and ran some carbon rovings and a layer of 4oz glass up the fin. It's now got a layer of bog on, waiting for a sand back and paint.
It's now a lot stiffer and a bit thicker, hopefully you'll notice a big improvement.
Should be ready by Saturday.
if you didn't i'd be interested to cut one down to 18.5
how much 
