Are there any plans for a military-style drum? I'm thinking of the ones used by Napoleonic and Civil War era drummer boys.

Welcome to the forums, oif-retread! I like this idea, especially if the drum attached to a soft-plastic bandolier. A lot of folks consider drums to be one of those things that are best conveyed through round bricks and tiles, but if BF made a bandolier on which one could mount a 2x2 round brick, that'd work too. In high school, our marching snares were carried with harnesses instead of straps, but i doubt anyone wants to give their minifigs the same back problems i had

I had considered the round brick and tile method, but it just doesn't seem the right size. I've seen a fabuland lego drum on bricklink, but I'm not sure if that would work either.

Like you mention, I thought something on a bandoleer would work (similar to the messenger pouch/mailbag that TLC does) for a side carry. Or perhaps something that could slip over the neck so that it could be worn in front.

I support this!

I like the harness and Bandolier ideas.

I also think this would be a great idea. I visualize both a softer bandolier-style strap harness for older uses, and a hard plastic over-the-head harness for more modern uses. If/when I get time (probably after BrickFair), I'll try to upload a picture of my altered Lego pieces that served as my drum harnesses last year. Proper drums would be wonderful as well - 2x2 round brick/tile combos work for bass drums, but a new diameter is needed for snare drums. Again, I'll try to show my poor solutions later on, but I would love for BrickForge to render my butchery of Lego pieces unnecessary!