3Doodler’s 3D-printing pens have always had a lot of potential (who doesn’t want a souped-up glue gun that can draw 3D structures in midair?), but in our hands-on with the pens, their rough build ...

The original 3Doodler came to be after a hugely successful Kickstarter campaign in 2013. Project backers funded $500,000 on the first day and the final total raised was $2.3 million. The Pro model ...