Looks good. I have 2 done so far with the hose clamp. Heatshrink tubing looks like a great idea.
To initially apply the magnets, I used JB KwikWeld. I did them one after the other doing opposing sides of the housing. Even so, they started to slump towards each other a little until I put on zip-tie and the tape. The JB Weld alone may hold, but I am going to do the heatshrink.