Three squat 15 ml bottles with conical inserts, a 10 ml blunt-tip syringe, a small polypropylene funnel, and a sheet of blank adhesive labels. The inserts matter: a conical insert lets a converter draw the last 2 ml out of a bottle at an angle, which an open-mouthed bottle will not do.
The use case is travel and the use case is sharing. A 50 ml glass bottle in a bag is a liability; 15 ml of three different inks is a fortnight of writing and will survive being sat on. The bottles seal on a conical cap with a silicone washer and we have carried them on aircraft without incident, though we would still put them in a bag rather than a pocket.
Wash everything in warm water before first use — the bottles are moulded with a release agent on the inside. The syringe is also the right tool for refilling spent cartridges.
