Bottom bracket: Is 3mm significant?
 

I have some left over parts and wondering if I could sell a crankset with a 110mm bottom bracket if 113mm is recommended.

probably not, depends... like obsessing over this stuff?

It really depends on the frame that the crankset and bottom bracket is going onto, whether this would work or not. If you are selling this as a set, I would give a full disclosure to the buyer.

The easiest solution is a spacer. They are about $4 a piece where I am. Come in different sizes, just get a 3mm one. They go on to the fixed cup of the bottom bracket to push the bottom bracket out essentially.

Just sell them separately and stop fretting over it. Both sizes are dirt common.