Strictly revolvers? It would start with a new cartridge with a belted case. Belts are the original improvement on rimmed straight-wall cases, and they allow more chambers within the circle of a cylinder while maintaining a minimum cylinder diameter yet still headspacing properly even with a rolled crimp. I believe this was first innovated on straight-walled cases by H&H but has been implemented in a revolver previously by FA with the 500 WE. I propose such a case of a diameter for 0.400" bullets and 1.29" case length.
Using this new cartridge, I propose a revolver with a cylinder of diameter the same or similar to a Redhawk or S&W N-frame with seven chambers. Even the smaller N frame would chamber seven, whereas an L frame or GP-100 would hold six, and even a K-frame would hold five. But I propose a large revolver, not like the Redhawk and with novel features. One such feature would be the automatic ejection of moon-clips upon fulling opening the yoke. It could be accomplished with a spring-loaded ejector rod. Because rimmed cases are not used, the conventional spider would be omitted. Unintentional ejections could be prevented with a positive detent that would be overcome by the weight of the cylinder falling unimpeded. With the Ruger push-button cylinder release, this would allow the strong hand to maintain a firing grip during reloading and the support hand would only need to bring the new clip to the cylinder and close it. We've seen eject-on-open in the past with top-breaks, so this also isn't entirely novel.
That's all I have for free revolver advice.
For handguns, I propose some factory Ruger No. 1 handguns. For handgun hunting, this would beat the hell out of revolvers.
For autoloaders, a compact single-stack nine. By compact, I mean at least as big as a G48 but it could have a longer frame.
For rifles, MPR in 6.5 Grendel. It seems logical to do a Mini-30 in Grendel, but there is no point, so like the one in 6.8 SPC it would be a waste of time.