Intro: Logitech Audio Wireless Bluetooth Speaker Adaptor - Range Extension
I modified the range of the bluetooth audio device in the title by removing a 3mm thick steel plate in the base, which is there only to provide weight and a good grip to the rubber feet. The pictures show the only steps, the glue used is very soft and easily removable.
You'll need a small phillips head screwdriver and a flat blade (blunt is better so you don't damage the case/feet)
I tested about 12 feet max range through one wall before, and over 25 feet through two walls after. I also had great success with turning the device upside-down, which extended the range to the entire house through any walls.
It should all disassemble easily, prying glued parts off of each other should be done slowly and carefully. Haste does not pay off in a 10 minute job, as cracking the casing won't make you feel good.