Saw these style boards on Oriental Trading for use as geometry boards. Wondered a diy hack. Use glue on bottom circle of thumbtack to secure it from being plucked out by little fingers. Sowdering About in Seattle: Toddler Busy Boxes
An Easy DIY Geoboard for Kids: Just using an old cork pot holder, the kids are able to make their own pin designs with this simple geoboard. Push pins can help to develop the fine motor skills needed for writing.