Created this case as my Roku Premiere was constantly displaying an overheating message. Simply pop the cover off your Roku and slide it into this case. The top has a cutout for a 20x20mm heatsink secured with some thermal tape. The Front Covers takes 4x M2x10 bolts.
Attached are the .f3z Fusion 360 archive files so you can modify this design to your liking or to fit whatever heatsink size you'd like.
In the last pics you can see I removed the metal shield from the PCB and replaced the thermal compound on the CPU as well as added thermal pads to the RAM. Getting the top shield off isn't too hard, it just takes some patience. Slowly pry every nub latch on the shield until it starts to come up, being careful not to damage any of the tiny SMD 0201 or smaller parts.
Link to just the PCB Model on GrabCad: https://grabcad.com/library/roku-premiere-pcb-1
For more info & downloads: https://www.thingiverse.com/thing:5023744