Has any one made there own fin

Need a weed fin but look like I need to spend $100 even 2nd one cost $80

I am pretty sure I could make one with $10 buck of fiberglass I got in the shed

Any tips ?

Was thinking may be use plywood , shape it and fiberglass the out side
Or
Cut out fiberglass shap , use a little bit of resen , let it dry hard , then use that as the base and build it up .

Thx will

THx moby
once again you have provide me will all my answers