My Schecter is missing the battery plate so I decided to look into purchasing one online, and couldn't find any that were the right size for my Schecter. I decided to make one. I didn't have the tools or skill to cut one from plastic so I just found an old silicon/rubber iPad case lying around and decided to cut one from there. Actually came out pretty nice. My question is, is using rubber/silicon as my battery cover safe? I know they are usually made out of plastic with some sort of silver lining on the back.

The silver lining is a conductive shielding tape; it's there to prevent interference with the signal coming from your guitar. There's probably nothing terribly unsafe with what you're using, though it may prove less durable* than if you'd used a hard plastic, or even wood.

*Not in a "will fall apart in a week" kind of way, but where the screws go through might take a beating with a lot of battery changes.
dspellman Yes. They don't have the part. My only option was to make one. Just want to make sure that using rubber/silicone is safe to use a battery cover.
Nothing unsafe about it. If you had a nitro finish it might discolor the area around it, but I don't think Schecter does any of those.