Download the Amoreon clothes designer linked below. The download also includes the templates for drawing your clothes on top of. Have a look at the instructions in the download for more detailed info. (The Designer and Viewer are the same app and download).
Open one of the included png temmplates in an image editor
Place your new clothing image in the following folder
with the approproate name (torso.png, arms.png, legs.png)
Now choose your settings for matte/shony/glossy, opaque,fade,transparent, for each of the torso, arms and legs.
Name your outfit and press X to build the final output ready for the game.
Grab your new folder from the following path
(download path)\AM_Designer\ClothDesigner_Data\StreamingAssets\YOUR OUTFIT NAME
and place in the game folder at
(install path)\???????\YOUR OUTFIT NAME HERE
Open the game in sandbox mode and you will see the outfit on the customisation table.
For a more detailed click by click guide please watch the video tutorial above.