Does it need the battery cover to on the camera?

Hi! You can cut up an old plastic gift card into roughly the same shape needed.

Fit it into the space making sure it is thick enough to put some pressure on the batteries to hold them in place and secure it 1st with paper tape, then 2nd with electrical tape.

You can alternatively use:

•Cardboard

•Mending Plate

•Cork

•Or even the battery compartment cover from another device, such as another camera or an old remote, etc.

If you'd like, can also check out this eBay Listing: for a pretty reasonable price for the replacement cover for Nikon D3000 that includes free shipping, if you're willing to wait from 2 - 4 weeks for it.

(Of course you don't have to use the url above and can do your own search for any store/site you choose.)

And this YouTube tutorial on How to make a Battery Grip Compatible with a Case.

Hope this is helpful for you!