I have seen lots of cases for component testers with the ZIF (Zero Insertion Force) socket on the front but the model that I have is different (having a screw terminal socket instead). There are advantages and disadvantages of the screw terminal over the ZIF socket which probably boils down to personal preference but I have designed a case for this model and I don't believe I have seen one for this model to date.

Print both parts with the outside face flat on the bed. I printed all 3 parts individually. Base could be printed with no supports if your printer is good at bridging but I used supports just in case. Lid does not require supports. I used a brim as the surface was quite large and did not want the edges to curl up. I was not watching my first layer and I have a slight blemish by the screw hole where some filament had got caught on the hot end whilst heating up but previous iterations had all printed fine.

Once printed you will have to remove the screws from the bottom of the tester PCB, place the unit in the printed base and then use M3X10 bolts ( I used button head hex, these will sit nicely in the countersink) to screw it into the base. Then the top screws can be removed from tester LCD and the printed lid with button inserted into hole (plunger end on inside of case) can be placed on top. This again will be screwed down into the tester standoffs with M3X10 bolts. If you intend on installing a battery first I suggest you stick a little foam on the inside to stop it rattling. I found battery power to be unreliable when using the tester so I only use the power jack.

Change Log:
After printed the model shown in the pictures I slightly thickened the screw supports in the lid as there was a couple of thin walls. I elongated the power jack hole after I realised my jack was mounted on the board wonky. I moved the top screw access hole a slight nudge towards the top. Any issues you get give me a shout and I will advise.

20/08/2019
I have blown my component tester and replaced it with a very similar model but in doing so noticed a couple of differences (mainly TH components and not SM components). The button on the new model is slightly different and shorter so I have included a longer button stl. If yours is a different length you can always stretch it slightly in cad or slicer. Due to the longer button I also added a spring to mine (not necessary but a nice touch to stop the button flapping around). I also had to use an exacto knife to further elongate the power jack port, I didn't feel the need to waste the box and reprint.

Check out my YouTube channel DonLabs for some basic electronics tips and tutorials. My video on the use of multi-meter includes the use of the component tester and also a video on how to better utilise the screw terminal socket.
https://youtu.be/6aWe66QK5N0
https://youtu.be/uasB_2nvYtA

Creality

Ender 3

No

Yes

0.2

15-20%

With the Hobby King orange PLA I found 200°C hot end and initial bed temp of 67°C works well on my glass bed. Bed temp was dropped to 59°C after a few layers. As this was not a particularly structural print and most of the inside would always be hidden I printed with 2 walls, 3 top layers and 3 bottom layers (with a 0.2 mm layer height this gives a top and bottom thickness of 0.6 mm).
Initial layer speed 20 mm/s
Outer wall speed 26 mm/s
Inner wall speed 39 mm/s
Top and Bottom layer speed 25 mm/s
Infill speed 41 mm/s
Initial Travel speed 55 mm/s
Travel speed 95 mm/s
5 mm Brim

Roughly about 1 hour 45 mins for the lid
4 hours 30 mins for the base
10 minutes for the button
This is for my Creality Ender 3 and different printers may vary.