Pathio lets you adjust where support pillars are generated on your model by painting directly on your 3D models. To start, select your model and click the Custom Support button. To start with, click the Autofill button to generate supports in all the places your model usually needs them (those parts will turn blue). This is based off your Maximum Unsupported Overhang Angle, which can also be set right here in the manual support pane.
To actually adjust where supports will be generated, click on Paint Custom Supports. Now when you left-click on your 3D model, you’ll mark triangles for support. Right-clicking will clear supports off of the selected triangles. Triangles that overhang a lot in your model will turn red if they’re not supported, or blue if they will be supported.
For easier selection by default, the paintbrush tool only selects triangles that touch each other and are within your Maximum Overhang Angle. If you want to select parts of your model that are separated by non-overhanging areas, turn off the Paint Contiguous Areas option and keep painting. To remove all support structures from your model, click Clear Supports.
When you’re done painting supports, you can deselect your model, or simply click Slice.