This might not be the correct forum for this post, but I thought McDermott's new weight system was interesting. The butt has a CF core with a sliding carrier in which a weight bolt can slide. It allegedly provides a wider range of balance points than a regular weight bolt:
www.mcdermottcue.com
Here's the patent application with more details if anyone is interested:
It looks like the entire carrier is removable.

H-Series Pool Cues
Your struggle to get a perfectly-balanced cue is officially over. The H-Series is the first line of cues ever to feature the fully-adjustable VBP weight system.

Here's the patent application with more details if anyone is interested:
US20200188766A1 - Adjustable weighting sytem for a cue stick - Google Patents
A cue for use in billiard games includes a removable weight system located in a bore in a butt section of the cue. The weight system includes a carrier having a length extending from a first end to a second end with one or more weights and two or more support washers supported on the carrier. A...
patents.google.com
It looks like the entire carrier is removable.
In operation, when the cue 100 is fully assembled, a user may insert a tool such as an Allen wrench into the opening 180 at the first end 176 of the engagement piece to unscrew the engagement piece (with bumper 172 attached) from the butt section 102. Once unscrewed, the user may then remove the VBP weight system 150, including butt plate system 170 and carrier 160, as one unit from the support tube 120 secured in the butt section 102. The user may then slidably adjust the weights 167 and support washers 165 into a desired configuration as described herein. Once, the desired configuration is achieved, the VBP weight system is re-inserted into the support tube 120 located in the butt section 102 and the butt plate system is re-secured into place by engaging threads 182 with threads 184.