You build a Mechanaut's Apparatus with ample room for upgrades and improvements. Its blueprints are based on the Apparatus of the Crab, but you can model your apparatus to resemble any Beast or a Humanoid.
Entering and Exiting the Apparatus
A creature within 5 feet of the apparatus can enter the apparatus and become its pilot or exit it. Doing so costs an amount of movement equal to half its Speed (round down). The apparatus can only fit one Medium or smaller creature in the pilot's seat. Any creature within the apparatus has Total Cover from all effects originating outside of the apparatus.
Piloting the Apparatus
The apparatus acts on its pilot's turn, and doesn't act unless it is piloted. The pilot sees and hears through the apparatus's sensors, gaining the benefits of any special senses it has.
On its turn, the pilot can direct the apparatus to move (no action required). The pilot can use the apparatus to take any action (other than the Magic action), Bonus Action, or Reaction. Only you can make attack rolls while piloting the apparatus, and use your Intelligence for attack and damage rolls. The apparatus gains the benefits of the pilot's class features and feats, but can't be used to emulate a magical effect.
Remote Control
While the apparatus isn't being piloted, you can command it to wait or follow you. While following, it moves on its turn so that it remains within 30 feet of you.
Repairing the Apparatus
If the apparatus drops to 0 Hit Points, each creature inside of it is ejected in a space within 5 feet of the apparatus and has the Prone condition.
You can take the Utilize action to temporarily repair the apparatus while it has 0 Hit Points. This repair allows it to move, but it has the Incapacitated condition until it regains any Hit Points or finishes a Long Rest.
The apparatus gains the benefits of taking a Short or Long Rest as normal. If the apparatus is lost, you can build a new one for 250 GP.
Customizing the Apparatus
The apparatus comes with two integrated weapons, one in each of its arms. When you finish a Long Rest, you can replace these weapons with Simple or Martial weapons of your choice. Only one installed weapon can be Ranged. Each integrated weapon is wielded as if with two hands. If you integrate a Masterwork weapon into the apparatus, you gain the benefits of your Masterwork Bonus when attacking with it.
At Craftsman level 13, you can apply an Armor Enchantment (except Resistance) to the apparatus. At Craftsman level 18, the apparatus gains the benefits of your Spellwrought Armor while you pilot it.