Mangadonf
I had a couple of ideas for stuff that Alex could try to build. 1. Maybe he could get even stronger by turning himself into the devil version of the Angeloids from Heaven’s Lost Property. 2. Customized weighted clothing for his friend Sairorg. 3. Bottled Resorts from Negima that Alex could sell or keep for himself. 4. Kakugane from Buso Renkin. 5. Maybe he could study the research from the Church’s Holy Sword Project that Kiba survived to create a new type of evil piece that would grant the recipient access to the bloodline power of the giver(for example this piece would allow Kiba,Akeno and the others to wield Rias’ Power of Destruction.