Cheapest on Amazon PLA
I had the best luck printing with a 3-layer raft in Slic3r Prusa Edition with supports only turned on where the clasps were overhanging and rotated 45deg as to cover the most amount of surface area. I recommend using the .stl files with the thermal tabs as that caused the least amount of warping.
If you have a small printer like me and can't print the whole thing at once you'll need to super glue the pieces together. I added tabs and sockets to the edges of the front, back, and handle - use these to align the parts correctly (you may need to do some sanding/filing to get them to fit cleanly and leave a seamless edge). Due to print orientation, both the handle and back only have sockets where they attach so you will need to supply your own tabs. I just used the purge blob that the prusa makes before each print.
If you choose to do so, you can print the fan bracket and add a 120mm fan to the rear top of this cover. I found that the airflow was lacking since the Thunderbolt board controls fan speed based on temperature.
The .step file is included in this thing so you can mod it to your heart's desire!