This is a tiny footprint case for stacked Wemos D1 mini esp8266 board and Mini560 dc-dc buck converter. 

D1 mini sits on the bottom of the base part, Mini560 is secured on the cover part by small clips. Solder necessary cables on your boards and slide parts together (tight fit). Cover part has two pins that hold the D1 mini in place when parts are together.

There are holes for USB-C power cable, reset button, jumper cables and ventilation.

Dimensions of the case are 13x27x37 mm.

I printed mine with 0.12 layers.