A claw-based inserter concept from when all machines had to stack vertically on top of each other in a clean and obvious way. This is probably the closest concept before we got to the final design.
A top-loading design in which each inserted had a crane-game-esque track that connected directly to conveyors and machines.
A more refined crane concept. It allowed for a few nice QoL features like scaling length, but was ultimately scrapped for various reasons.
A couple earlier versions of the overhead track. They proved to be too bulky and complex for the animations to fit actual throughput in game.
The Inserter was one of the most critical machines to get right for Techtonica, and we spent a lot of time sketching and prototyping various ideas to make sure that it both felt intuitive to use, but also fit into the grand scheme of a megafactory. Over the course of a playthrough, the player would construct and place hundreds, if not thousands of these Inserters, so the UX was extremely important. I made modular prototype assets for all of the designs that we wanted to test in game. We ended up going with a more classic Factorio-style design in the end, but I still like how some of the early concepts felt in smaller scale factories.