OctoPrint is the snappy web interface for your 3D printer
G-code generator for 3D printers
G-code generator for 3D printers (RepRap, Makerbot, Ultimaker etc.)
Raspberry PI distro for controlling 3D printers over the web
The open source mesh processing system
Optimized firmware for RepRap 3D printers based on Arduino platform
FW for ESP8266/ESP8285/ESP32 used with 3D printer
An open process control and laser engraving software solution
DIY project to build a cover, flat panel or combo flip-flat panel