doubtful that you should take a grinder to your foils.
wood is a perfectly good material to make new ones. you will need to glass them. they need to be quite strong so stringers are great. put one at max camber for easy shaping.

foils for the foilboards are cut from aluminum billet on a cnc. some big windsurf fins are made that way. heavy and accurate. g10 on a cnc is a good way to make a windsurf fin. heavy, accurate, expensive, right amount of flex for a board.
when H16 first came out we were forced into making rudders because the abs ruuders couldn't handel the loads.it was a while before lexan rudders were invented, so a whole market sprang up to supply usable rudders. the molded ones were glass with mysterious fillers, and the custom ones were wood. there was lead in the wood blades because rudders had to be 7 or 10 pounds(whatever the rule is). i always thought my wood ones were a speed advantage. the best tornado blades were custom wood with glass in those days.