Stacking: Silks and sheets of metal
 

Reading patch notes is a dangerous thing. I remember when these didn't stack, but didn't realize how late it was when they got changed. Patch notes of July 10, 2001:

- Spiderling and Spider Silks are now stackable

- Spider Legs are now stackable.

...

- All Sheets of metal and Folded Sheets of metal are now stackable.