I've been working on a texture pack, I haven't made much progress yet but this is what's done so far:
Diodes: Fire Diodes: Shoot Cursor: (First - shoot, Second - shoot-cursor) Health Bars:
What I did is that I replaced the files in the data/resources one by one. Actually when making mods like these it would be nice if the author would make a zip file that would be extracted at the data level and fill in all the particular files. However we hope to provide an official mod manager to address this issue in the near future.