Accessible Geometry - Transversal across Parallel Lines

Introductory (plane) geometry textbooks and websites have many valuable illustrations of geometry concepts and principles. This 3D-printed model is my first attempt at making those illustrations accessible to students with visual impairments, as well as other students who may be tactile learners.

Your feedback for improvement would be appreciated, especially if you are a special education teacher working with such students. Is it sized well? How well do the angle markers work? Any better or standard ways to mark congruent angles for visually impaired students?

If you're interested, we have a discussion thread on "Students with Visual Impairments" in my "Teaching with 3D Printing" Thingiverse group (http://www.thingiverse.com/groups/teaching-with-3d-printing).