Voting equipment - State government design and manufacture

Is there anything legally preventing a state government from designing or commissioning the design of its own election equipment?
Note, I’m not really asking if it would be a good idea or not.

As it currently exists, its seems like private companies bid on the contracts on a state by state basis.

No legal reason. States purchase voting equipment because they don’t have the facilities to manufacture their own and it’s far cheaper to buy from a manufacturer than it is to build them.

It’s no different from the state buying vehicles: they could conceivably make their own cars, but why do it?