Would it be possible to erase the building then redraw the parts of the grid within the area that get erased too? I’m not on an iThingy at the moment but I’ll check it out soon.
This redraws the grid as long as the eraser can be drawing. The redraw grid ability is everything in the when object is cloned except for the destroy block.
You could replace the last touch y > 120 with checks to see if last touch is close to the current clone’s lines. That results in the grid not redrawing in some areas if you erase really quickly. The solution to that is to expand the distance to last touch. 100 is not enough.