Geoff - thanks for the compliment
Here are a series of the technique I use.
1) Lay resistors down and solder to 3mm solder wick braid - outer edges set 20mm apart. If you are careful, you won't get solder spreading too far.
2) Cut the excess legs off.
3) Cut a strip of plastic (from a Coke bottle or something similar) 2 cm wide and lay the resistor strip on top before slipping 25mm shrink wrap tubing over the lot.
4) The other side. Join both sides at the right circumference by overlapping 2 inches and then put yet another heat shrink over the join. I also usually wrap a 2cm strip of felt over the OUTSIDE so that it sits snugly inside the flange. The felt stops quite an amount of direct heat being transferred to the metal - and serves to heat the air in proximity instead.
5) Applied to a refractor project.