Sven said:
I just slip them into the bottom section of the cartridge they came in. I've seen this on a few blades, so I'd be surprised if only a few brands have that feature.
I think you probably will be surprised then our Sven. Around 80% of my blade choices / tryouts have been paper wrapped and then packed in little card boxes of 5 including all the current Gillettes (all ranges including 7 o'clocks + Superthins), Lords (full range), Shark, Tiger, Bics, Rapira, Racer, Supermax, Personna, the list goes on, it seems to be the preferred manufacturer's packing nowadays.
Plastic cartridges are fairly uncommon now, the only ones I've had in plastic dispensers have been Feather, Derby, Wilky Sword and old stock Gillette Swedes. What are you using at the mo out of interest?