What I want to do
My attempt and results
I started from a pre-cut pattern in Tyvek (this part was precise, I think I'd pre-cut the patterns in a workshop), and then taped down the McDonalds' straw spars recommended in the plan with 1" masking tape. I stuffed three straws into each other, end to end, and I lined them up by eye and taped them down. It was very messy and I didn't fold in any reference marks or anything:
I similarly applied the 1/4" PP strapping tape (brand: Tesa 4288) for the bridle attachments entirely by eye. They are slightly uneven.
Then I tied the bridle. Here I made sure the bridle point was in the exact middle.
I flew this kite and it flew great. I haven't gotten a good in-flight photo yet. I was suitably impressed, and it flew better than the version I made very carefully with bamboo spars.
Questions and next steps
My goal is to use this kite as a wind speed meter and need to calibrate it. I need to get a better clinometer and spring scale setup. My current spring scale is 5000g, @Ecta64 is recommending 250g scale. I should really attach the clinometer to a tripod or other leveling system.
I also need to replace the stretchy dacron line with a non-stretch line, as recommended for a kite anemometer (wind speed meter). I bought 3000' of 70lb kevlar line from Emmakites.
I should try a version out of a plastic bag, not just my fancy type 10 Tyvek.