This tool from Thierry Delattre in France aims to conveniently replace a compass / set square / protractor / ruler.
It's fun to use and works well: at a basic level and a more advanced level: see it reviewed here by Ed Southall co-author of Geometry Snacks.
As he says: "Anyone who has taught constructions at school will be familiar with the typical frustrations that come about regardless of how well you plan for them: super loose compasses, students jabbing each other, compasses with the pencil fastener missing, students getting cross because their compass slips as they’re drawing a circle, or they wobble it as they try to figure out how to manoevre their hand 360 degrees around their other hand. It’s a tough unit of work, if only because of the frustrating elements of the equipment we use. And so I was pretty excited to find what could be a solution to all this – not to mention a possible money saver for schools."
Tarquin now provides three ways to buy the ThaMographe in the UK: this set of 10, singly and a class set of 30. For other options see below.
See a video of it being used to construct a triangle.
See more uses of the ThaMographe in the video here.
Have fun or do advanced geometry like these images: