The traplines can even be made simpler.

I do advice using a bead instead of that figure 8 plastic thingy. The latter seems to do really well in eating through the line.

For 7 years now I use 3 mm dyneema line where I have made loops using a double figure 8 knot, Rock climbers know what I mean here. Personally I use a plastic thimble in the top loop where I tighten the loop in the line by stitching, however friends of mine have used only the line loop for long times without problems. At the bottom I put the line through the handle of secure it into place using a figure 8 knot or even better a blood knot (figure 8 with an extra rotation of the line around the line). Then at the very bottom another double figure 8 loop. This loop is permanent and it is secured to a stainless steel ring or shackle using a fishermans hitch. This knot can be tied and undone without fiddling with the line. Just move the line loop through the eye and cross it back over the eye itself. Dissassembly is in reverse. The fact that the bungee and the running line with dogbone is later attached makes becoming undo impossible and acts as extra security.

The ring or shackle replaces the ball bearing block and works just as well if not better as they don't bend out of shape or wear out. By careful to use shackles with circular sides and no lefts over barbs. Tie the dogbone to one end of the running line (fisherhitch again) and run the line through the ring or shackle. Tie a loop in the other end after you have slid the bead on the line. A sheet bend is the right not here (if that is the correct English name). This loop can easily be adjusted thus repositioning the bead for the right height of the trapeze. The loop itself can then be hooked by the bungee using a plastic hook. For quick trap height adjustement use the two rings of the dogbone.

This setup is by far the most inexpensive and most easy to make and will last for years. My 3 mm 500 kg break dyneema lines have so far survived 4 years of sailing and open air storage at the beach for 6 months each season. I weight close to 90 kg and sail in rough seas often.

Component list :

3 mm / 500 kg garanteed dyneema line
A plastic thimble (if so desired but can be doen without)
A plastic handle
A stainless steel ring of small diameter or a smooth small shackle
A short piece of 5 mm abbresive resistant dyneema line
A dogbone
A plastic bead large enough to not pass through the ring/shackel
A plastic hook
Bungee cord (I use 4 mm max as the dyneema trap lines are so light that they don't need a large retaining force)
Needle and thread if you want to stitch the thimble in tight.

Good luck

Wouter