This requires BepInEx 5.4.23.4
https://sourceforge.net/projects/bepinex.mirror/files/v5.4.23.4/

Kithack Engineer
This mod allows you to create part variants from stock parts with revert and file management. 

Steps

--Cloning Files--
To open the menu press Alt+P
Next, in the UI, Select the file to clone
Enter a name for the new file, then click on Clone
After clicking on Clone you will be taken to the custom parts window for modifying files. 
You can select the part to edit and click on Quick Edit or Raw Editor
Make your changes and click on Save
Once the save is completed, click back on 
Next, click on the Clont Part tab and then click on Reload
Reload will reload all the parts in game and let you play with your new part. 

--Deleting Files--
To delete a file, go to My Parts tab and then select the file to remove
Then click on Delete

--Editing Files--
To edit a file, click on the My Parts tab and select the file
Then click on Edit Config