I've got wood

It has to be able to take the impact from another object (bike tubing, other mallets, body parts, walls) at a full swing (whatever that force may be... As hard as someone can swing it with one arm, really). It doesn't need to be particularly whippy or flexible. You should be able to lean on it (so overly flexible rods, like many newer golf clubs, are not ideal).

Weight is probably the most important aspect after strength. Some of us have been using ti, but it's really quite heavy. I had some bamboo that was great weight-wise, but would only last a week or two max. One direct hit with another mallet and it would split.

Has anyone tried wrapping a bamboo mallet in any sort of glue impregnated cloth?

I would imagine it might cut down on splitting?