Don't want to mount to your HVAC unit using screws? Use magnets instead! Print two of these to mount to both sides of the device.

Requires:

• M5x6mm (x6) Hex head cap screws
• 18x5mm (x4) round magnets (neodymium recommended)
• If your batteries are not 5mm tall, you can glue a cardboard spacer in.
• It should be a very tight fit (i had to tap them into the hole), so no glue may be needed. Otherwise you may need some superglue or epoxy