Neat trick to get wires through heatshrink too long to thread by hand.
Step 1: Materials
1 ring magnet. The smaller the heat shrink, the smaller the ring magnet. Ring magnets can be as small as 3mm outer diameter and 1mm inner diameter. That is small enough to go through 1/8inch heatshrink.
1 small ring. Again the ring outer diameter has to be small than your heatshrink.
1 magnet. Doesn't matter what size.
Step 2: Thread Wires Through Your Ring
Step 3: Put Ring Magnet Into Heatshrink
Then pull the ring magnet through the heatshrink with your other magnet