I'm in search of advice for the best methods of making holes in plastic. I'm currently laying some new salad beds, and using co-extruded white/black plastic (1.4m wide) that I expect to be able to use for 5+ years. I need to make loads of holes approx 12"x12" apart (for lettuce, etc).
In the past I have used a range of methods from using a serrated knife to mini-blowtorch to jet-flame lighter, but none have been that satisfactory. I accept any solution not using a tractor will be slow, but at least need something that makes it less arduous. Once the holes have been made I can re-use the sheets again and again, so the time is well spent.
The ideal is to have a circular hole (so plastic doesn't flap - like when using a knife to do a X-shaped cut), and/or a sealed edge (to give it more strength over time - like when using a heat-based solution).
So I'm really after a good solution that is relatively quick, accurate, cheap and doesn't involve a tractor or some crazy engineering! Any thoughts?