If you use the DSS gauge mounts there's a much simpler way. Tie a knot at the end, pass the bungie top-down through the lower left hole, then down-top through the upper left hole to make a loop for the wrist, then tie an overhand knot in the bungie and bring it top down through the upper-right and down-top through the lower right. You don't need to tie the ends of the bungie together or use any zip ties.
The overhand knot in the middle will slide back and forth between the upper holes, so each loop grows when you put your arm through it then shrinks back when the whole thing is on and stable. You end up with a mount that is easy to take on and off but also quite snug and tight. If it is too wide with some suit (i.e., if you sized it for drysuit but are wearing the gauge with wetsuit or skin dive), you just take the overhand knot in the middle, and pull it down in front of the gauge, and it will tighten and stay tight. Also, if there is a cut anywhere in the bungie, because of the overhand knot in the middle only one loop will be affected and the gauge won't fall off.