Summary

Uses rounded blocks and wedges to create a stone arch doorway. Door width, height, number of blocks, thickness and edge curvature are customizable.
Source code includes block and wedge objects which could be used for wall, path and castle making.
EDIT (2014-8-11): Changed design to use hull around spheres, added base, functionalized structure, rotated structure to be more easily buildable, made handle thickness more robust with geometric mean