The can bottom is cut off about 8-10mm from the edge where it starts to curve to the circular 'foot'. It may take a while to find a way to do this that suits your tools. beware that the edges can be very sharp, gloves are a good idea. My method:

1. Cut the end off roughly using a knife.
2. Use a woodworking marking gauge to scribe a line around the outside of the can
3. Use metal snips to cut the end off.

The can bottom should then push into the slot in the print.

If you want a magnet then a 10mm x 3mm should push into the recess. You may have to heat the plastic a bit, or sand the recess out a bit as the magnets vary a bit in size. Or find one that fits, which is what I did.

The can bottom can be removed if you want to by prising it out with a knife, carefully round the edges.