There is a company in Netherlands (not the UK, I know) that MIGHT sell the Editor pen kit. I can't say for sure.
On a Google search for the Editor there was a "hit" and the fabrication/assembly instructions were shown.
[URL unfurl="true"]https://www.houtdraaiwerken-penkits.nl/wp-content/uploads/2016/12/BP181-Editor-pen-kit-Assembly-Instructions.pdf[/URL]