Ok, here we go…
CPU: Intel® Core™ i7-9700K
RAM: Corsair DIMM 32 GB DDR4-3600 Kit
Mainboard: MSI MAG Z390 TOMAHAWK Z390
SSD1: Mushkin Pilot-E 1 TB, SSD (M.2)
SSD2: Patriot Viper VPN100 M.2 1 TB, SSD
Power Supply: be quiet! STRAIGHT POWER 11 CM 550W
Cooling Unit: Corsair Hydro H115i PRO RGB 280mm watercooling set
Display: Lenovo L22E-20, Gaming-Monitor (cheap, all buttons on the front, all connectors on the back and pointing downwards, VESA fixing points)
The suitcase i used is this one:
But if i’d had to do it again, i would choose a case with a bit more height… it’s very, very tight in there!
I disassembled an old PC-case and cut out the bottom plate with all the fixing points for the mainboard, then i simply glued it into the suitcase (after i was really sure that everything else had enough space and was accessible as well). For the rest i built a frame of aluminium-profiles and covered the top with aluminium sheet-metal.
The suitcase has a Powercon socket for the main power connection (the other components are “hardwired” to this) and i placed two XLR-sockets which are connected to the balanced outs of the audio interface (Focusrite Scarlett Solo). The audio interface has still to be integrated somehow, but i not yet sure of how to do it… build it in vertically (for that i had to cut out a piece of the top frame) or hide it under a lid which would open by just pressing the on top (i already bought some spring-supported push openers for furniture). We will see… 
Oh, and i had to use two dampers for the lid of the suitcase to keep it in place (30N are good for this!)
Some adaptors for LAN, 2nd video connection (Displayport to HDMI), USB-Hub, flat profile TRS-plugs for the audio cables (lack of space & height)…
So, i hope this answers your questions - if there should be more… just ask. 
Cheers!
Erik