I've included 4 files. One standalone gremlin, one with custom supports combined, one with the supports alone, and a simplify3D factory file all setup with supports and stl's for an i3 style printer.
For the custom supports, use a separate process if your slicer supports it. Supports print settings are 1 bottom layer, 4 top layers, 1 perimeter, and 0% infill. If you use those settings with the custom supports, print times and material used will be considerably less than standard generated supports.
Settings for the lightest gremlin possible (for paratrooper use) are as follows: 2 Bottom layers, 2 perimeters, 4 top layers, 10% infill. Any less than this and I had some ugly prints on my prusa, more layers or infill and perimeters is fine, but the weight goes up a lot,
Another note, if your slicer supports dense support layers, add in a couple at 95% to get the cleanest part possible around the head and arms.