How do I make a mod?

Modding support it the top suggestion:
https://www.simplerockets.com/Feedback/View/y1Bgz8/Modding-Support

The status is "in progress". So hold on tight!

@mjdfx150529 I couldn't if I wanted to. Can't get the mod tools to work

@momoking8289 Yep, don’t use them on your crafts for now, they will break in the future.

@mjdfx150529 Okay, ill check those out, thanks! In return, I will tell you about something I found in Partlist.xml. There's a hidden part called light, with the description: "TODO". This probably means that we're getting lights pretty soon.

There are modding tutorials for SimplePlanes on the Jundroo YouTube channel. They could work a bit. You should wait for official modding support on SR2 to come out though.