I’ve spent some time with compasses for geometric construction and can offer the following: - Accuracy is key when doing geometry, but it isn’t easy to achieve. Higher quality instruments are important for precision.

• You’re right about blunt points. the blunted points are intended for young students who can’t be trusted with anything sharp. You need a real steel, needle point for accuracy.

• Stay away from plastic compasses altogether, for the same reasons. Plastic flexes too easily and will give you inaccurate arcs.

• Compass with a center wheel Staedtler Engineers Compassor other screw mechanism will allow you to keep exact radius settings for multiple arcs.

• Good brands to look for, IMO are Staedtler, Rotring, or Alvin. Drafting tools had their heyday before computers began to replace them. Vintage instruments on E-Bay from Dietzgen or Kueffel & Esser are frequently available for a modest price. Search for ‘drafting equipment’.

• Check out Geogebra.org for their computer-based geometry and math apps; free for all and very sophisticated.

Good luck! This is a fascinating area for intellectual exercise; a game for one player with a long history.