From the article introducing the podcast:
The Gemini PDA by Planet Computers brings a much loved form factor back to the world of smartphones – the clamshell, keyboard-based palmtop. In this episode, MEX founder Marek Pawlowski talks to Martin Riddiford of Therefore Design and Davide Guidi, CTO of Planet Computers, and hears the story of Gemini’s development and successful crowdfunding campaign. It is a tale which traces its roots back over two decades, to the days when British computing pioneer Psion was at the forefront of mobile innovation. The conversation explores how Martin’s design work on those Psion devices informed today’s rebirth as the Gemini PDA and looks at the design challenges Planet has overcome to bring this new product to market.
Now, bear with the podcast audio - get past Marek's introductory few minutes and then get past the echoey audio and occasional break-ups, because the content of the podcast is very interesting. Martin goes into detail about the design decisions that had to make when re-creating the Psion palmtop concept for 2017/2018. From thickness to keyboard to camera and telephony, it's all here in terms of the challenges faced.
Well worth a listen!