Kickstarter campaign is live right now over at https://www.kickstarter.com/projects/martinschneider/blockface-a-stamp-kit-to-explore-typography-and-more
You can pledge for a DIY kit there if you don't want to source all the materials.

BlockFace is an easy-to-use modular typography printing kit consisting of 24 stamps, which you can combine to construct letterforms, design typographic posters and cards, and explore the joys of printmaking. It is a collaboration between us, the Open Press Project, and Will Mower, a graphic artist working in London. The kit was designed by Will and is produced and distributed by us.

Link for instructions on how to make your own stamp set: https://openpressproject.com/blockface