After printing a 3D model with only 5% support, it is still too difficult to remove support material without damaging the model. Is there some way in designing the model to reduce the support material dramatically?
Maybe. It depends on the model. Can you share the .skp file?
From my very limited experience (mostly reading, not doing), the need for support material stems from overhanging features in the object, such as the sloping sides of a bowl. The closer the sides are to vertical, the less there is a need for supports. If the object’s geometry cannot be significantly changed, then perhaps using a different material or different printing process could be chosen to reduce the need for supports.
Reorientation of the model might reduce the amount of support material, and modifying the support parameters in your slicer can reduce the difficulty in removing supports.