This is a case to hold a micro-SD card reader together with a ESP8266-E12 WiFi Module to publish the content of an SD-Card on a Web-Server for download. The circuit board is also 3D printed. The wirin is done by unisolated wires in the channels on the board. See picture. To be less sensitiv for temperature you should prit the board with ABS material. A schematic as well as the sketch to flash the program with Arduino environment is attached. In a short time you will find a detailed description of the electronic part on the AZ-Delivery Blog https://www.az-delivery.de/blogs/azdelivery-blog-fur-arduino-und-raspberry-pi/micro-sd-file-server-mit-d1-mini-8in-arbeit9?ls=de