There are many versions of record clamp weights, this is merely my take on them.
All are trying to achieve basically the same thing- to keep the record flat and to help grip the turntable surface. Additionally, they may add some improved stability and damping to the rotating platter which in turn may have acoustic benefits.
Commercial non-adjustable versions can range from the $20's to rather absurd, depending upon how fancy they are. And commercial adjustable versions are typically even higher priced. Essentially they are all just weights though.
There are now four designs using a top shell and a threaded-in base.
**Version 1, small diameter-** The smallest version can contain up to about 185 grams (6.5 ounces) of standard BB pellets.
**Version 2, large diameter-** The larger diameter version can contain up to around 275 grams (9.8 ounces) of standard BB pellets. It has a lower profile and larger diameter that may be easier to use on some turntables.
**Version 3, larger diameter, tapered with plain top grip-** This version can contain around 300 grams (10.5 ounces) of standard BB pellets if you load them carefully. It uses the same base as version 2. The top may be printed as a single piece or as a shorter base and a cap. The advantage to the two part print would be that it can be printed without supports on the outer surfaces. The cap can be bonded to the base by several methods including epoxy, super glue or ABS juice, depending upon the filament material used. A particular advantage to this style is that it covers most of the record label for stability but has a generous clearance at the top for larger cartridge shells.
**Version 4, larger diameter, tapered with fluted top grip-** This is identical to version 3 except that the top grip has eight flutes. It is a bit more secure to grip and looks interesting while the record is playing.
Any of these versions contain more than enough mass to accomplish the intended task without placing undue stress on the turntable's center bearing. However if you want more weight, you could either scale up the height of both the top and bottom pieces (to keep the threads matching) or use lead pellets.
The BBs do not move around during operation, they settle into place nicely. If you want a bit of additional damping, simply add some foam tape to the base. For example- https://www.lowes.com/pd/Frost-King-0-125-in-Foam-Plumbing-Pipe-Wrap-Insulation/1069439 This will also help to protect the record labels from wear.
The center hole must be reamed to 0.282" (which is 9/32" or 7,15mm) to fit standard center pins on turntables snugly but not bind.
I chose the outer diameters so that they would not interfere with the tone arm. The center hole extends all the way through on the non-tapered versions in order to accommodate longer record platter center pins. The center hole is present on the bottom surface only for the tapered versions and will accommodate pins up to around 7/8" (22mm) in length.
These weights do seem (at least to my ears) to improve sound quality a bit, but nothing I could put numbers on. Their greatest benefit certainly is to help flatten out any warp or bow in the records which keeps the tone arm and cartridge from bouncing up and down as it follows the grooves. Less stress on the needle suspension and tone arm pivot points for sure.