Improved Polydron panels

The original Polydron panels consisted of triangles, squares, pentagons, and hexagons, all with identical side lengths, which cleverly interlock to enable construction of various 3-dimensional shapes. (See e.g. https://www.polydron.co.uk/construction/polydron-class-set.html). I had much joy with mine.

See also the [compatible Polydron Frameworks version](https://www.printables.com/model/1064344-polydron-frameworks-collection), for your printing pleasure.

Based on years of use, a number of drawbacks to the original Polydron panels were identified:
1. Cost and availability, being high and low respectively. The rate of exchange of the British pound does not help and neither does residing in the colonies.
2. Durability - over the years I have had to retire quite a few of my precious panels, mainly due to cracks in the plastic finger acting as a spring to allow the interlocking mechanism to engage, and to stay engaged.
3. Tightness of fit - perhaps related to the previous problem, not all