Konstrukt is an SVG + ECMAScript application for compass and straightedge construction. It's not too unintuitive to use, once you know what the controls are:

- to draw a straight line through two marked points
- press the
**v**key and click on the two points - to draw a circle centered at one marked point through another
- press the
**c**key and click on the two points (the first of which is the center) - to delete a marked point and all edges through it
- press the
**x**key and click on the point (tip: you might create extra lines and circles for the purposes of deleting at an intersection) - to move the viewpoint
- click on empty space to center the view on that position
- to zoom in
- press the
**PgUp**key - to zoom out
- press the
**PgDn**key

New in Konstrukt version 2 are some more attractive drawing tools that are locked to the construction points, useful perhaps for mathematical diagrams like the above *3 octahedra around a line in a 24-cell*:

- to draw a line segment between two marked points
- press the
**s**key and click on the two end points - to change the line segment thickness
- press the
**-**key or the**+**key - to draw a filled polygon
- press the
**f**key and click on as many points as you like, then press the**z**key - to change the fill colour for future polygons
- press the
**[**key or the**]**key