Since the controller board that comes with the Tevo Tarantula is apparently not designed to handle the current necessary for heating the bed to print ABS without catching fire, a MOSFET expansion board is needed. Being a technician, I could have easily built one, but when you can get one on Amazon for eleven bucks - https://www.amazon.com/gp/product/B01MY50JL3 - why bother? It does need an enclosure, however.
This case is designed to be used with the MOSFET controller boards marked "www.cbd-3d.com V1.3". A 30mm fan is mounted behind the heatsink to aid in cooling. I suggest orienting the fan so that air is pulled through the box and out the fan, thereby sucking heat out while bringing cool air in the front grill. The control wires are brought out the front through the horizontal slit.
While designing the box, I modeled the board itself just for the hell of it. I haven't printed the board model, but I am including it in case you want to. If you do decide to print the model, please post photos so we can see how it comes out.
Make sure that the lid is oriented upside down to eliminate the need for supports. Support may be needed for the model of the board, though, since the MOSFET would print in mid-air otherwise.
This was the third box I printed. On the first try, the mounting holes for the board didn't line up - I forgot to measure twice, print once. On the second go round, I didn't take into account the length of the fan's mounting bolts/nuts. Finally, on the third try, I got it right. Only on the last print, the center piece of the fan opening got knocked over during the print! If you look closely at the rear of the box, you can see where I printed the insert separately and glued it in place. And let me tell you... this was CLOSE. I had just a little over a couple of feet of filament left when this case completed. That was too close for comfort!