Chassis is the whole speaker holder, chassis disks cylinder (with battery and board). What usually happens is people tend to use something like speaker holder 5 that has a lip which can be secured between 2 pieces this way the rest doesn't move, assuming you connect the disks to the speaker holder via the rods.
Securing the RICE port via hot glue is iffy, and again, I think you might find that you have less space than you think.
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