MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
I use aluminium spacers with nylon washers top and bottom instead of springs to space the bed from the carriage plate, The nylon washers are just to decouple the heatbed from the plate so it's not acting like a heatsink. If your going to flash the firmware just use vanilla marlin at least then you are getting the latest version plus there is a config already made for the Ender 3. Also once flashed do a proper PID tune of the heatbed and hotend and remember to put M420 S1 in your start gcode to enable the mesh before each print it should come after your G28. There's also a line in marlin that should be enabled to reuse the mesh after homing just can't remember it right now and don't have access to check at the moment.