These are mostly done in flat acrylic craft paints and model paints. The knee and elbow pads are made with Milliput sculpting putty.
The belts and straps are all made from craft foam.
The weapons are made from a combination of wooden dowels, toothpicks, and random plastic.
Ralph and Leo’s weapons have a lot of extra detail put into the handles.
The headbands are made from real fabric to look like they are actually blowing in the wind.
Here is a shot with the original Playmate TNMT figures to the left. 