I ...printed the white parts of the case each "in one piece" on a Flsun QQ-S Pro. This worked great and so I didn't have to worry about gluing it all together.
The designer of the Arduino Portal Gun used a 2.5 inch tube because he lives in the USA. I had overlooked that when I printed the "modified_collector.stl" part. So I needed an adapter to be able to use a 60mm acrylic tube.
So get the right tube and print the right part before you print ;-)
Otherwise you can use my adapter "PG Acryl Rod Adapter.stl".
Or you print the right part from Lunchbox7985: "modified_collector_larger_center_hole_original_outer_size.stl".
The last modification is for the Generator Hatch.
I modified the case cover to fit a total of 3 arcade switches. The white button is for "Cancel Portal" and only lights up when there is a portal to cancel. (You need a slight modification of the software for the Arduino, I attached the source code file, and you have to connect the LED from the white arcade button to port "A3" of the Arduino (right next to the connectors for the two portal buttons)
The Cancel button can be operated comfortably with the little finger.
The power-up switch (in the middle) can be operated with the knuckle of the ring finger.
You can use PG-Grip_R.stl and PG-Grip_L.stl from the original Portal Gun Design from Evarate (https://www.thingiverse.com/thing:3579224)
The three black cables are each 32cm long and come from the hardware store (Home Depot): H03VV-F 2×0,75mm² and mounting with hot glue in their mounting points to the big white part.