making your own daggers/rudders

every now and then someone asks if they can build their own foils

here's a good pretty good guide

http://www.smalltridesign.com/Trimaran-Articles/Construction-tips/dagger-board.html

Good link, if you just need a replacement for a non-racing boat. The latest gen boats have foils that require molds, or at least very meticulous construction, for accuracy in order to properly operate in the laminar flow region.

I guess if you have the time, money, and skill you might save ten bucks.