So after looking on the forums here and elsewhere I figured out how to have enemy part weapons made. Today, I loaded up Unsealed Door and brought my first enemy part to be turned into a weapon, he did it, and I quit the quest because he wouldn't turn my other items into weapons. However, when I loaded the quest again Dr. M just talked to me like he did before I completed Doc's Secret Plan.
I guess my question is, why? Will I have to complete all the quests and open up the ability to repeat quests in order to convert multiple enemy parts?