The BUNDLE command is used to hold together skinnable items or tanned/cut pieces.
To bundle raw skins:
Have a skin, pelt, or other item from skinning in one hand and a rope (not a horse lead rope) in the other. To add a skin to a bundle, the bundle must either be in your hand or be worn. Then, with the skin in hand, type BUNDLE to add your skin to the bundle. If the bundle is tied, you can not add to it. Bundles can be sold just like single skins. Use UNBUNDLE to untie the bundle, but be careful because the UNBUNDLE command dumps all the items in the bundle on the ground.
To bundle tanned and cut pieces of skins, hides, etc.:
Have "some <item> pieces" in each hand (for example, "some rat-pelt pieces" or "some boa-skin pieces"). Type BUNDLE to combine the pieces. Note: you can only combine pieces of the same item -- rat-pelt pieces can only be combined with rat-pelt pieces -- and of the same color (if they have been dyed).