How have you used dragon parts in recipes?

[VelvetViolet]

My son's gnome fighter had red dragonhide plate armor made from the scales of a red dragon the party slew.

I also had a green dragon use large pieces of its eggshells to "infuse" an unborn elf with the half-dragon template; he not only had the pregnant mother using the eggshell piece as her bed (she had been taken captive in his cave during her pregnancy), but ground up pieces of eggshell into the gruel he fed her each day. Sure enough, when the baby was born she was half elven, half green dragon. (She ended up being the queen of the PC's small kingdom in the follow-on campaign, though, so it all worked out for her.) But I wanted there to be an alternate route to the half-dragon template other than "dragons can mate with anything."

Johnathan

Some Chinese, Korean, and Serbian fairy tales include stories of various creatures (e.g. humans, koi, snakes, roosters, rams) ascending to dragons.

The means might include acquiring a dragon’s pearl, a wishing stone, jumping the dragon’s gate, or living a really long time.

 

[Sir Brennen]

In my D&D campaign world, red dragon dung is the critical component for black powder. Consequently, black powder is pretty rare.

I know we had a D&D campaign where dragon scales were used to craft a shield which gave resistance to fire, like the movie Dragonslayer. Could have sworn the rules to do that were from an official source, but it was a long time ago.