This is a remix from Weaktwos (https://www.thingiverse.com/thing:3451519). I've added enhancements to adjust the size of the platform, insert, and added an option to cutout a piece for a usb port (as my couch has on it). Download the OpenSCAD file and use that to customize the dimensions as you need to.
Default platform diameter is 104mm and the insert diameter is 85mm. The rendered STL files included in this Thing uses those options.
I've added some configurations to make a cutout on the opposite side of the USB cutout to accommodate any buttons that may be there like there is on my couch.
The rendered STL uses the same 104mm platform diameter, 85mm insert diameter, 8mm USB depth, and now 70 degree cutout on the opposite side.
The OpenSCAD file has also been reuploaded in case you want to make modifications for your specific use.