TL;DR
Various items such as the firearms and certain equipment grid items are crafted only once and could be integrated into the UI instead once researched.Just like how blueprints have no crafting cost, the steel axe was removed in 0.17 and, according to FFF-379, in 2.0 various other items like will be removed such as the "remotes" and wires.
What/Why ?
In a game that is pretty much all about mass production and scaling up the factory, there are a number of recipes/crafts that are only ever used once (except in case you die and have to "start over").None of these items have a high crafting cost in terms of material either so it's not like it would remove some intentional hurdle.
Any Firearm:
The firearms (pistols, submachine gun, shotgun, combat shotgun, flamethrower, rocket launcher) themselves are the most straight forward example as you craft them once, equip them and then never think about again. Maybe you'd craft them twice/thrice to increase your ammo capacity.
Instead of having to manually craft the weapon it could just be a selectable option in the armory slot. You click on the weapon and get to choose which weapon is equipped for that slot. It could also remove the "pistol of shame" that you get whenever you respawn if it was no longer an item.
But what about the spidertron and its four rocket launchers?! Both the car and the tank have weapons without actually being included in the crafting recipe. The four rocket launchers make up 80 iron and 30 copper of the 1.1k iron and 7.2k copper required. It could be replace with like 50 green chips to somewhat maintain the cost or something like gun-turrets to maintain the idea behind it.
(Has anyone ever actually crafted a pistol intentionally in a vanilla game?)
Nightvision and Belt Immunity:
All equipment grid items have the effect where, by equipping more, the effect becomes stronger. Except these two. Both exist to remove minor annoyances which are darkness and being pushed around by your own belts.
The belt immunity in particular even has only a 1x1 grid-size to be as minor of an inconvenience as possible. It could be integrated into the exoskeleton such that once you research belt immunity, the exoskeleton gains that ability. Disabling it could either work through the same toggle as disabling the exoskeleton itself or a separate one.
Nightvision could either just be automatically enabled once researched or perhaps integrated into the power armor with a toggle like the others. NV might have a combat use if you fight a biter nest during the night but I feel you're better off just equipping an actual combat item instead.
