I've been doing a design study (read "having a blast mucking about in the VAB") plan a heavy LKO station. One thing I've found working in 2.5m and 3.75m sizes is the wanting to cap (terminate?) one or more containers in one go. I've had a hard time figuring out what to put on the end.
In 3.75m doing PXL-PPD + PPD-PTD + the cute PTD endcap makes for a lot of steps to come down from 3.75.
In 2.5m, obviously one doesn't want the PPD foil showing. Cap it with... a battery? I actually whacked a NF 2.5m monopropellant tank on the end of one; the four spheres looked good [and you never get to see 'em!] but again, felt like a hack.
This is all about aesthetics, of course, so none of it matters but I was wondering if anyone had any clever suggestions?