This is an update of my original case.
The snap fit is better on this case.
The top and bottom is beveled a bit.
The holder for the wemo has slots to make the wemo easier to remove.
I have removed some of the side walls for the wemo holder to use less filament.
I am more satisfied with this version than the previous.

25% PETG is plenty strong.
I use 230 degree head and 80 degree bed.
I had warping on the bottom of the pieces at 68 degree bed. An article suggested that I
increase the bed temp which seemed opposite to me but I tried it and it works.

For Weather Station, Octoprint monitor or your own project.
Small and simple it holds the Wemos D1 mini and the 1.3 OLED screen.
The case snaps together.
You can see in the pictures that to hold the screen in place, I put a small piece of the foam that comes on the pins of an ESP8266 or ESP32 to protect the pins in shipping.

The USB connector end of the Wemos slides under a lip to secure it.
The opposite side of the Wemos is held by a little bulge on the back wall.
So, the wemos can be completely snapped in.
If you wanted to, you could use a soldering iron to melt over the pins that the OLED sits on to more permanently attach the OLED.