Some folks have listed their build parts in this thread. I've tried to put together a list of 120mm AIOs that might fit Mjolnir:Can someone start an public excel sheet to share what parts you use with this case? More important are CPUs, motherboards, RAM, GPU, PSU, coolers, storage type (no. of SSD/M.2). Anything else?
120mm AIOs for Mjolnir
This is only based on manufacturer's listed sizes (and a couple of confirmed builds). What AIO is compatible with your setup will also depend on things like RAM height, motherboards heatsinks, cabling, etc.
For build part lists, PCPartPicker.com is a great site for sharing your build. Much easier than sharing excel spreadsheets, and can alert you to potential incompatibility issues (but not case-specific size constraints.)