Step 2: Mounting the speakers
Wash and dry the soup cans thoroughly.
Press the cans onto the foam to give you a rough size to cut.
Cut circles of foam, but trim ~ half an inch off two sides, you'll need this to get the foam into the cans (see later).
Press the speakers onto the foam to give you a rough size to cut.
Cut enclosures for the speakers, in this case the rectangular holes grip the magnet assemblies.
Taper a round edge to accommodate the speaker-cone, and ensure there's room for wire to pass through the foam block.