I also have a PLB (the exact same one as yours actually - the McMurdo 210) coming in today or tomorrow. I'm thinking about getting the OMS canister instead of the custom made one
- can put more stuff into it (saw another board member stuff a plb, a vhf radio, and some other items in theirs), and its 45 bucks or so online
The only problem I see is where to mount it (the oms tube doesn't have 2" slot). ]
Check out this link for mount ideas. Scroll down and look at the canister for the can light. They use large hose claps, taco clips 1 inch d ring and quick links
Underwater Dive Lights http://www.OMSdive.com
There is a thread in the DIY section about making your own canister out of pvc pipe that looks interesting.