"In order to get a controlled break along the score, force needs to be applied on both sides of the glass."
Not true. A series of sharp taps with a hard object along the score will also work. That's the purpose of the spherical knob on the butt-end of a standard steel wheel glass cutter: to tap the score in cases where it's either difficult, impossible, or inadvisable to snap it. While this is generally done from the opposite side of the glass from the score, it will work if done from the same side.
I speak from experience: the "gifted" program at my elementary school did a unit on how stained glass windows are made, and the students working on their projects (a small hanging planter made from ordinary window glass, and small ornaments made from stained glass) were required to tap, rather than snap, on all but the smallest cuts (and so I never really learned how to do it any other way)
"In order to get a controlled break along the score, force needs to be applied on both sides of the glass."
Not true. A series of sharp taps with a hard object along the score will also work. That's the purpose of the spherical knob on the butt-end of a standard steel wheel glass cutter: to tap the score in cases where it's either difficult, impossible, or inadvisable to snap it. While this is generally done from the opposite side of the glass from the score, it will work if done from the same side.
I speak from experience: the "gifted" program at my elementary school did a unit on how stained glass windows are made, and the students working on their projects (a small hanging planter made from ordinary window glass, and small ornaments made from stained glass) were required to tap, rather than snap, on all but the smallest cuts (and so I never really learned how to do it any other way)