Mercere magi predominantly with some commissions from House Verditius
Mainly non-Mercere Hermetic magi
A roughly equal mix of Hermetic and Hedge Magic sources
Predominantly allied Hedge Magicians
Most of their devices are inherited as heirlooms from their predecessors
They use their own hedge magic traditions to create many devices
An eclectic mix of Hermetic, Hedge, Divine and Faerie sources
Other (please expand)
Every since my "Epic fail" with 30 Redcap Magic Items I've been thinking a lot about the origins and diversity of Redcap Magic Items. At some stage I think some sort of "Starting Redcap Magic Item Packages" might be useful based on some of the published Redcaps and listed by spell level range ie. (2 10-15 level items, 1 level 20 item etc) with some options but in the interim I'd like to step back and take a wider approach.
So who exactly makes these items?
It's suggested but never clarified in the ArM5 corebook that Redcaps possess Hermetic items but with the arrival of numerous interesting Hedge (and Rival) Traditions that can produce useful items (not to mention Divine relics, Faerie items / External Vis and the possibility of Infernal artifacts), this seems a bit less likely - particularly given the small number of canonical Mercere Magi and the likely even smaller number of dedicated Mercere artificers.
The majority of their magic items were originally commissioned from other Hermetic magi (there just aren't enough Magi Mercere to go 'round, though some do indeed work as lab rats for the good of the House). House Guernicus and House Mercere have several agreements where Mercere gets a share of some of the plunder the Quaesitors take (such as, if a magus is required to perform service to the Order, Mercere might get an item made), and the Mercere are also rich because they're the vis bank (and because they're the most organized part of the Order).
Hedge-magic is much harder to find because the Order doesn't practice it much.
My vote (why do you allow up to 4!? Most of those options only work exclusive of the others being true!) went to mostly non-Merceres. House Mercere does not have enough people in general, much less dedicated artificers, to supply that many Redcaps with items as rewards become necessary to give. In fact, there's a group of magi dozens of times larger than the collective magi of House Mercere who would assist in this. This group is every magus with a vested interest in keeping their messages and traders willing and able to deliver messengers and manage their trade of vis and items. Many magi realize how vital Redcaps are, and are willing to put in time to help them because that will increase the efficiency of the magus's own operations in the future.
As for non-Hermetic sources of items... Hedgie items are too rare and often too weak to be worth it, and the magicians from Rival Magic are pretty much nonexistent in the Order because they have the power and capabilities necessary to take a third option when a magus gives them the Join or Die.
Thus, there are probably lots of magi from multiple Houses putting in a season here or there to keep the Redcaps supplied with the items they need to do their jobs better and feel good about doing so.
There is only few hedge magic items which will be more efficient than their hermetic counter part. One particular useful one I can see is a Rusticain magic (non Ex Miscellanea) able to craft items granting Wilderness Sense or other useful Supernatural abilities.
Regarding Faerie items... sure if you can trust them and not get dragged into some drama.
I think that enough redcaps have magic lore that enriched items of virtue (from RoP: Magic) are going to be pretty common. But, aside from that, I see their items as being almost entirely from Hermetic sources. I think enchanted devices are often handed down from redcap to redcap.
The way I see it is redcaps are members of the order. They choose not to vote but they are magi by legal right. They're likely to get vis as part of their membership in covenants and I see them as likely or more likely to go out and find vis in the field as other magi. They can't use this vis themselves, they can use it to commission rituals and enchanted devices. The house also has profits from their banking concern and their unparalleled knowledge of mythic Europe's vis sources to draw from. for redcap PC's in my game (the one time that I had one) they received enchanted devices from their virtue in addition to collecting vis and trading for them with the other PC's (which made the character rather powerful but still a few rungs lower than a gifted magus).
I imagine that the majority of Redcap items come from random Hermetic magi. The rates of pay aren't stellar (1 pawn per 10 lab total) but Redcaps can usually pay in the kind of vis you'd want, and I'm sure House Mercere has a large stock of clear lab texts on the most commonly sought items (so magi can use all of their lab total and House Mercere gets several items). This will make it attractive vs. just distilling Vim vis.
For the larger, custom stuff, they'll probably pay Verditus rates to Verditus magi. This will be for stuff that is 6th magnitude effect and must be designed specifically for someone to avoid regular Warping. The Verditus are the best candidates to manage this, but they won't accept Redcap rates (probably).
There will be a catalog of inherited items, though wear and tear on items will reduce this somewhat (even swords and jewelry wear out over time unless specially enchanted to be resistant). Redcaps will tend to be harder on their stuff than sedentary magi, after all.
Another thing to keep in mind is that Redcaps have a lot of use for low level items - say, level 5-10 after all modifications - whose effects magi could reproduce just through spontaneous magic - often even non-fatiguing. This opens up for Redcaps two important sources of magic items of little use for ordinary magi.
First, "season remainders": when a magus has those extra 5-10 levels of lab total from investing another effect with the same TeFo combination, he'll probably add an extra low-level, utility item to be be gifted to or traded with Redcaps (or mundane powers).
Second, "idle apprentice seasons". If you are busy elsewhere, it's generally better to have an apprentice of moderate experience churn out items in his area of specialty, particularly if working from a lab text, than to have him extract vis or copy books (I'd also say it's more a far more fulfilling and "high profile" job for the apprentice, but...). Even a starting apprentice can easily generate a lab total of 10; one of middle experience a lab total of 20; and an experienced one, particularly if having appropriate Virtues (a focus, puissant MT etc.) lab total of 30 or even 40 in his specialty.
As for diversity, I realized today that some items would be relatively common, although they might vary in specific form.
Traveling shoes, to help traverse barriers. This might be water-walking shoes (boots, whatever), snow shoes, flying shoes. Depends on the area.
A vis scale and a vis transfer - a method of enabling vis trade. The scale (probably a beam scale) could be the transference device as well. You can't count on all the mages you encounter to have the necessary spells to make vis trades, or to have a day to make each transfer.
Also, what to a mundane would be a fortune in precious or semi-precious gems as vis carriers (flasks?) Precious stones are the most effective carriers, holding up to 15 pawns. The Redcap might wind up with a strange collection of tiny and small noble metal items at the end of a journey, in vis change.
A way of lightening the Redcap's mail pouch would be popular, too, I think. Shrinking enchantments?
Anything that will keep you warm and/or dry. There's a good piece of Redcap fiction somewhere that mentions one of these - along with a stern warning to never, ever tell anyone about it, not even your lover, "because she will tell her father, and men will kill for something that will keep them alive in the cold." Something that lets you see at night. Something that does The Wizard's Sidestep, which is incredibly powerful in melee and at range. All of these are low level items and super useful.
Redcaps would probably carry multiple tokens, each with 1 pawn. This makes the Redcap's end easy. HoH:TL mentions chess pawns. Any magus wanting to trade vis would likely do the same.
Making the items look less valuable to mundanes is probably a good plan, so even using animal teeth or wooden beads on a string would be a good plan. A vis scale is definitely a good one, though.
Those would be parchment scrolls, would they not? Not too heavy, though keeping them undamaged would be useful (though a simple box can do this fairly well).
Good point - a woolen cloak enchanted to keep you warm and dry, which I suspect both wool and cloaks have a bonus toward.
The scale is easy to enchant too, if I've done my calculation right.
Multiple tokens will work. The chess piece idea makes a good little story, but no chess queen can carry a vis queen. Vis tokens are more limited in capacity. A gold staff would only carry 40 pawns. You'd have to have a gold staff studded with diamonds for a full queen in a single object.
How much they would weigh would depend on how much mail is coming through, but I suspect carriage enchantments would still be popular.