| Azothath |
Generally you can make stuff out of special materials rather than the ordinary material, at an increased price usually. Whether there is a mechanical benefit(it does something in the game) is another matter. The benefits are defined and if you do something else there is probably no benefit other than the objects physical properties (hardness, hit points, weight).
Many of your questions move into home game territory. In a rules thread people generally stick to the core rules or rules as written(RAW).
You might try the advice or the homebrew sections.
| VoodistMonk |
Leather belts are by no means uncommon. And if he is trying to reduce his weight, by all means necessary, and is even trying to reduce the weight of individual items of clothing using special materials, there's nothing in the game that denies him this. Special materials have special properties for this exact reason.