I hope this may be helpful for anyone looking for a canister but struggles to find one they want.
The Delerin canisters are pricey because the are turned from a solid blank and must be hollowed out on a lathe to create the canister. I got my two canisters from a former cave diver that used to make dive lights. He wasn't diving anymore and was clearing out his light making gear. He had two unfinished canisters with lids that were not drilled and the latches, so all I had to do was align and attach the latches and I had a working canister.
Before doing so we talked so he could give me some advice on how he did that step. While talking he told me he used to make canisters from PVCbut people frowned on it so he went to delerin. You can make the same setup out of PVC and probably at a much cheaper price point. If you like DIY, you can get a hold of some schedule 80 PVC pipe of the correct inside diameter to hold what you need to house. Make sure you measure your PLB or phone etc corner to corner as that is the longest dimension that needs to fit. Get a flat sheet of PVC of the right thickness to create a top which attaches with latches and a bottom that gets glued in with regular PVC cement.
My pictures below are of my delerin canister but the assembly of a PVC canister would be the same. For the top and bottom cut two circles each one the dimension of the OD and two the dimension of the pipe ID. The bottom needs to be a snug fit for the ID circle. You would then glue the small circle centered on the large circle. This bottom piece would be glued into the PVC pipe to form the sealed bottom. Do the same for the top but the smaller circle in this lid shouldn't be real snug as an o-ring will form the seal and the top shouldn't be hard to get off. Once the top is formed go to McMaster and Carr and order a package of sealing O-rings of the size to fit your lid. I got square profile O-rings to get three larger mating surfaces:
O-ring on lid
McMaster-Carr
get some latches, many choices here. Mine look like this:
83314-LALB Latch/Strike – Nielsen Hardware
Get the appropriate dimension screws like this for your wall thickness and for the lid clasps. Stainless steel tapping screws for plastic.
McMaster-Carr
The lid can take deeper screws but depth is critical in the latch mount to the wall. You get one shot at placing them so care should be taken when placing, drilling and affixing the latches. A caliper and a drill press where exact drill depth can be set are your friends, but it can be done with a hand drill and some tape on the bit as a depth guide if careful. When affixing the lower part of the hinge, first make sure that the top attachment bar aligns up where the lid clasp will be
with the O-Ring in place on the lid and making sure that the placement leaves enough space to screw the catch into the lid. Once the sides are affixed use double sided tape to place the the lid clasp in he right location to catch the latch bar. You have a little bit of play side to side but you need to get the placement up and down on the lid so that the latch can pull the lid down.
You can see the placement on the lid here:
You can see I secured mine here so the latch is slightly below horizontal.
It could even be a bit lower as this setting is tight could be a bit easier to open if it wasn't so tight. I did this second one a bit lower and it feels better.
This is just to create a seal with the o-ring as water pressure will keep the lid tight once you head under. You just don't want it loose and getting jarred. Getting the latches attached is the trickiest part because the screws don't back out. If you mess them up you will likely damage everything getting them out so be sure of your placement. Using double sided tape helps alot unless you have a patient second set of hands. When screwing them in dip them in a bit of sealant. This will help lubricate the screw as you affix it and if for any reason the wall was slightly penetrated it would seal it back. If your screws are slightly long a dremel cutoff wheel works well to shorten them but takes off some of the self taping threads so don't go overboard. Make sure that you use a drill bit that leaves enough PVC for the screw to tap into but not so tight that you can get the screw seated all the way since you cant back it out.
My canister is 3 7/16" OD and 2 7/8" ID and 11 1/2" long including the lid. I can house a ACR PLB, foil blanket, signal mirror, 2 glow sticks and a sling string to whirl the glow stick or attach myself to another driver while drifting, Pheonix Jr IR beacon, and two granola bars with some room to spare. Attached to the outside I have a SAR 6/25 rescue streamer