I did this one a little while ago and forgot to share it. I hope you like it!

Here are the two scripts I mentioned earlier. They will be located at the bottom of the view menu.

Hello, got stuck in step 20. There are no bevel effects under Filters>Distort.
Which bevel script did you use in tutorial, I'd like to get exactly same effect, thank You.

Thank You Wallace!

I keep forgetting what filters and scripts are included with Gimp and which ones I have added over the years.
I thought for sure that this filter was native to Gimp.

Thank You Again!

And Yes, you can call me Moose. Most of my local friends do!

Layers Effect

Result

Thanks Wallace, got the hang of it have to try something more original next time with added realism
Your cap looks real nice, it bulges outwards just like opened cap.

Those are some excellent bottle caps!!

I created a bottle cap brush for anyone who is interested.
The more times you click the brush, the darker the brush appears.
Here are some bottle caps made with the brush.

I made a cap with one of my cube images dropped (and bumped) onto it and used the result for another
multi cap image.

One more, just because.

This is fun and simple. I had to post an easier one since my nested cube tut is confusing.

Wallace,
I love the Wallace Bunny!

I forgot to tell Wallace how cute his Easter Avatar is. Love it!
PhotoMaster, I really love what you have done with the bottle caps! Really nifty. I will do the tutorial for educational purposes to see how it is done. I also downloaded your brush. Thank you!