An idea for a lighter and more waterproof and perhaps even better performing swivel base.
People who make large (ones that look like massive mortar tubes) homemade telescopes called Dobsonians solved the swivel problem years ago. They use a flat sheet of formica on one surface, and on the other they have 3 pads of teflon. They also have a center bolt, but thats just to define the center of rotation and to keep the top from coming up off the bottom.
Some types of formica are better than others, but they all work pretty well. The teflon can be a pain because you can't really use anything to glue it to something else. You have to use mechanical fasteners, so the teflon has to be thick enough so that you can countersink your screws or nails, otherwise you tear the hell out of the formica in short order.
You can adjust the amount of effort it takes to turn it by adjusting the pad sizes and how close or far away they are from the center bolt.
The nice thing about this method is the friction is low enough that its easy to overcome, but its not so low that your things spin freely. Once you stop rotating, things pretty much stay put. And the stopping, starting action is NOT jerky, because unlike most other bearing methods/surfaces, the effort to keep it in motion is GREATER than the effort to get it started, so you don't get that push hard then break loose and move easy action you get with so many types of mechanical widgets. When done right, you'd swear you had thousand dollar bearings in there instead of something so cheap and simple.
You HAVE to use REAL formica and REAL teflon though. There is stuff out there that looks like both, but it isnt and doesnt work nearly as well. Do an internet search for telescope making supplies/teflon and you can probably find some. If you don't want to buy a giant sheet of formica, hardware and cabinet/countertop places often have scrapes for cheap.
Just an idea.
