A pen collection is an underrated part of the routine - the right holder makes a noticeable difference in injection stability, particularly at higher-viscosity doses. The 3D scanning and printing angle is the kind of community value-add that doesn't get enough credit.
The manual versus auto-injector preference tends to come down to whether the auto-inject sound-and-pressure mechanism causes anticipatory tension that makes it harder to hold still. For people who want to control the pace and depth, manual is usually more comfortable. Worth trying both before forming a firm preference.
On the topic of storage cases, one option holds twelve pens as an example. Plenty of similar options exist out there, worth clearly marking each one though.
Not here in the US at least. Mounjaro's still limited to the single-dose autoinjector style. Zepbound recently rolled out the quicker click-style pens, so fingers crossed Mounjaro follows eventually. Not a fan of single-dose pens, but tired of waiting around, so just going with what's available.