I have previously covered DIY prepreg using high TG epoxy and woven carbon. Until now unidirectional prepreg has been a problem but I've worked out a way of making my own, which means I can use the higher spec tow I use for filament winding. I am using Toray T1000 here which is 300 GPa vs about 240 for the commercial prepreg.

I set up the filament winder with a drum of appropriate diameter covered in non-stick paper:

and set it to hoop winding with an appropriate feed rate (2 mm for the 12k tow):

(sorry for the shit pic, camera autofocussed on the winder not the drum).

Whe finished I simply slice the non stick paper and cure in the oven to beta stage et voila, unidirectional prepreg: