Boardwalk PCB by /u/Shensmobile
I ordered the tray-mount variant of the foam because the top-mount version was sold out. I can confirm that the tray-mount works just fine on a top-mount aluminum xd64 case; it just seems to have a couple of additional cutouts for screwing down the PCB into a tray-mount case. Fits great, and works exactly as expected.
For the price, I definitely recommend purchasing this instead of cutting your own foam (trust me, I've tried.)
Quality is great, but it doesn't support my configuration, 2x 2u space bars in HHKB layout, so I needed to cut the foam to adopt it.
I honestly cannot express how impressed I am with the keyboard foam. It turned my boardwalk into a deep, thocky beautiful acoustic pleasure.
If you're on the fence just buy it, you won't regret it!
Boardwalk Plate Foam