My Seis (an Original and a Flamboyant) both fit into a Thomann E-guitar gigbag - https://www.thomann.de/gb/thomann_premium_gigbag_eguitar_br.htm (not at the same time). The only issue is that it has reinforcement where a single strap button would normally be, so the dual strap buttons have worn through. Loads of pocket size for straps, Zoom MS-60B plus wallwart, cables, notes, etc. It depends on what you're protecting the bass from - this stops the rain getting on them and protects against scratches and light impacts, and the bass always goes on top of everything else.
There's also a Rockbag for cricket bat basses - https://www.thomann.de/gb/rockbag_rb_20601b_steinberger_bass_bag.htm. I haven't got any experience of that as I just use the original bag with my Hohner.