HVAC Register Soundproofing Foam Hangers

I had an HVAC register which was carrying noise through from other parts of the building.  This was my solution for that.  It is a hook system that you can thread through a piece of foam to be able to hang it from a ceiling-mounted register.

To use this, poke each hook through the slot in the button and twist to lock them into the recess.  Then push the hooks through the foam and into the register grate and turn 90 degrees to hook onto the slats in the register.

Materials:

IMPORTANT!!! - Make sure to use a foam and a filament which is flame retardant.  I can make no guarantees as to whether or not this would meet your local fire code - you will have to check that for yourself based on the materials you use.  But the fact that this is near an HVAC duct makes flame retardancy a rather important consideration for this application.  Use at your own risk.

Additionally, make sure to use a filament which experiences very little creep over time, because the constant weight of the foam will tend to bend the hooks out over time if it isn't creep-resistant.

It's been a while since I printed this, but I believe I used a flame retardant upholstery foam and printed the hooks using a carbon fiber reinforced polycarbonate.