Hi @Føxtrøt!
In order to craft the platform hatch, you need a Hatch Hammer crafting table from the Platform Hatches mod, crafted at an Inventor's Table.
Place the Hatch Hammer on a wall and you can interact with it to turn a Draconis Hatch into a Draconis Hatch Platform (and vice versa).
You can also craft the blueprints for the Draconis Hatch Platform from this crafting table, and once you have learned the blueprints you can craft the platform from scratch at a Workbench, iirc. If it does not show up on tier one, upgrade it to tier 2.

Hope this helps!

the recipe for the platform hatch doesnt show up in the workbench, how do i get the recipe?