If you accidentally cut the wire how can you reconnect the rest of the strand back together?

If anyone else should come upon this question, these are low-voltage DC LED lights. The danger risk is quite low, if you apply minimal competency and common sense. To mend a broken solid copper wire, you would simply need to solder the break back together, and I would recommend that you encase that mended joint in hot glue afterwards to help stabilize it. There are tons of soldering tutorials available on the web that go over every aspect of the process, even the safety matters. Soldering is by no means rocket science and I've been utilizing the useful skill since I was a young kid. The total time spent mending a break shouldn't be any more than 10-15 minutes. Honestly, people who don't know what they're talking about shouldn't be responding to these questions. Doing so is not helpful to anyone.

How big is the battery pack? I need to use them for a craft and need to be able to hide it.

Hello The battery shell is: 2.76 inch length 2.09 inch wide 0.87 inch high I hope this can help you.

How long have these lasted for yall??

I bought 2 packs of the warm white ones. Neither lasted more than maybe 8 hours with new batteries. The colored ones just died and they last more like 20 hours. Maybe got duds but def won’t keep spending tons of money on batteries to take use these bc they each use 3 AAs.