I think a diabetic supply case at your local pharmacy will be what you're looking for.
I also wanted to comment on your aversion to PG aka Propylene Glycol. You do know that is an ingredient in asthma inhalers and thousands of other products? It's used as a flavorless, sterile compound to hold flavorings and medicines in stasis at room temperature and is a mild germicide. VG (Vegetable Glycerin) has a little taste (musty & slightly sweet), is sticky and thick and some believe that you would be more likely to have an allergy to VG than PG.
I prefer a 70PG/30VG up to 50/50 mixture myself. I don't like the musty flavor of VG but I like the added vapor it gives.
Also, if you like the Protanks, you may like the EVOD heads, too. They are cheaper & lighter but take the same coils as the Protanks. I have 5 filled with different flavors that I swap out all the time. I use my Protank & mini PT2 for my cinnamon heavy flavors but I have run apple-cinnamon & cinna-mint through my original EVOD heads with no problems. I am currently vaping an orange mocha mistake in an EVOD. It was supposed to be coconut mocha but I didn't label my DIY mixes and grabbed the wrong one--duh! I didn't like the orange by itself and somehow the mocha tamed the orange peel tang so it's a nice change & happy mistake.
I leave my heads on my batteries and always remember to turn them off when I put them in the travel case. I didn't at first and had the warm, wet spot issue in my purse but now it smells like apple-cinnamon so it's all good--LOL!
Vape on & remember, Backups for your backups! I have a generic 808 with 4 mini clearomizers (Like Halo G6) ciga-like set that I keep in my pocket for potty breaks at work. It came with a case for the clearos (or carto's), charger, pass-thru, and a PCC (Personal Charging Case).