Jack Hydrazine has created a 3D file for the enerjet fin can, this has made cloning the 1340 feasible. https://www.thingiverse.com/thing:3641770
The fin can has remained available in other kits, such as the Estes Eliminator for years, but even that has ended.
The 1340’s outside tube diameter is the same as the Centuri ST-13 and the Estes BT-56, but the 1340 used a thicker tube wall, the LT-125, which is available still from eRockets, although it is discontinued, so once they are out, they are out.
The 1340 had a plastic connector between the lower tube and the payload tube. I don’t have a real sample, so I’ve created a 3D connector that is similar what is represented in the instructions sized for the LT-125. All that is really important visually is the 0.1 inch band that separates the tubes.
I’ll also need to create a nose cone, as the ones I have are made for and ST-13/BT-56 and the shoulder diameter is too large. But the nose cone profile and size is correct.