With this program, you can generate a GameMaker:Studio extension from exported scripts.

Extension Generator

I tested the program, then there should be no problems. I remember that I am not responsible for any damage to your projects, make a backup!

Download (Google Drive)

Instructions

• [Optional] Backup your GMX project!
• Open your Project with GM:Studio
• RightClick on the desired Script folder and Click “Export Group of Scripts…” and save the “.gml” file
• Open “Extension Generator.exe”
• Chose your GameMaker:Studio project (.gmx)
• Choose the gml file exported previously
• Type the extension name and the Author
• Click OK
• Restart GameMaker Studio