Is there any sort of legal contract in the United States (Rhode Island) one could make without a lawyer that would state that a disclosing party owns a certain idea and that the receiving party may not use it or show it without the consent of the disclosing party.
This would not quite be an NDA, since the disclosing party has already told the receiving party about the idea in the past (prior to the signing of the contract). The goal of this contract is to prevent the receiving party from developing the idea (which originated from the disclosing party) into an actual device.