this is a fun game, arranging the machines and factoring in conveyors is a cool mechanic. the upgrades are cool, also. it's nice that you need to factor in every stage of production, and rearrange to prioritise them differently. its also nice that there's no penalty to a bad layout besides time (i.e. machines don't cost a currency to place) although it could be cool if you needed to craft machines maybe? so it felt more like the factory was feeding into its own growth beyond upgrades..
i'm having trouble understanding if machines are working, however and the lack of clear assets indicating the connected shape of each machine is also kinda a drag for how dense factories need to be..
my suggestions would be a new "active" machine sprite (could just change the color of the window) and maybe some kinda "joiner" sprite placed between each tile of a machine, perhaps (just like, a little dot between the two or something)