The anonymous illustrated pamphlet De rebus bellicis, which survived in the late ninth century Codex Spirensis, consists of a series of suggestions for reforming the Roman Empire. It was written after the reign of Constantine, which ended with his death on May 22, 337, but before the battle of Adrianople fought on August 9, 378 between an army of the Eastern Roman Emperor Valens and Gothic rebels.
"Reforms of Imperial financial policy, of the currency, of provincial administration, of the army, and of the law are proposed in turn. The writer describes a number of new mechanical contrivances which in his opinion ought to form part of the equipment of the Roman army. To facilitate the task of constructing them he included in his treatise coloured drawings of what these contrivances should look like when completed. More or less faithful copies of his drawings have survived in several of the manuscripts" (Thompson, A Roman Reformer and Inventor. Being a New Text of the Treatise De Rebus Bellicis with a Translation and Introduction  1).
A brief work which would have had small chance of survival on its own, De rebus bellicis survived in the Codex Spirensis, a collection of thirteen different texts, which was noticed by scholars in the early 15th century, and copied several times. Though the "original" Codex Spirensis was later lost, De rebus bellicis, and some of the other texts in the codex which did not exist elsewhere, including the Notitia dignitatum, survived through the copies made at that time. These copies appear to have included faithful renditions of the numerous colored illustrations.
Thompson cited above includes black and white reproductions of the images of imaginative machines in De rebus bellicis. The images, some of which are available on the web, are especially notable because they are copies of late Roman book illustrations, very few of which survived.