Just tried cutting out some vanes from a drinking straw that was lying on the kitchen counter. I just used some scissors, free hand.
After a couple minutes of experience (OP, hopefully you have more time in on this, and can contribute better tips...), I report that:
- getting an approximate spin vane shape is pretty easy
- getting precision (each vane looking like every other one) is way way more difficult
- I don't think the spiral cut on the straw is contributing anything (?) although I suppose you could harvest a slightly taller vane out of the diagonally cut material - probably would be easier just to slit the straw lengthwise to get your raw material
- for really cheap approach to a jig, I think I would cut my desired shape out of stiff cardboard (2 identical pieces), sandwich the flattened straw material between the cardboard pieces, and trim around the edge for each vane
- die cut would work better, but then there is the expense of getting that set up...
- not sure, but the smallish diameter straw I tried looked like the resulting vanes would perhaps be too curly; maybe better with a larger bore specimen?
- we have no info on 'stickability' of typical drinking straw material (will it stay on the arrow?), nor on durability of said material (lack of durability seems a common gripe with the commercial spin vane products)