[morzh]

I simply try to cut it where it won't be noticeable too much.
Say the cap is held by a clamp by its bottom side. So I cut it such that the cut will be concealed by the clamp.
If a cap is screwed to the chassis and has the cap separated by a groove, then I cut right at the groove and then simply glue the cap in place as it is not mechanically stressed.
If a cap is screwed but has the indent at the bottom, which is about 1/8" wide, then I cut at the very upper border of the indent, which serves two purposes: 1) the main cut part has no narrowing so the guts are extracted easier, and 2) the indent then, after some manipulation, can be inserted inside the main part which still preserves the caps' looks though the indent itself becomes a smaller groove.

Any way of cutting without smooshing the can is good.
When using band saw which produces very accurate cut, the cap has to be advanced a little at the time, first one turn, and then another, or else the saw will pick up the can damage it somewhat, plus there is a possibility of tossing it across the room. So need to be careful.