Instead of pets or mounts, what about MAGs?
Remember MAGs from Phantasy Star Online?
It might be interesting to see a similar function in SK. Feed your little buddy your spare materials and help it grow up into various forms that can provide you bonuses on deeper tiers.
This would also influence Auction House prices, as people would be spending their materials on their MAGs instead of creating as many auctions. Similarly, crafted items wouldn't appear in the AH as often, as players wouldn't be crafting using those spare materials as much.
Alternately, the developers could hit two snipes with one stone and tie this in to Guild Hall upgrades (which a lot of players seem very eager to get). Instead of individual MAGs/pets, guilds would get a "material deposit box" in their guild hall and deposit their spare materials in much the same way we do with minerals during gate construction. After a certain (hidden) number of materials have been deposited, the Guild Hall undergoes an upgrade process and builds itself a new wing, merchant, view, bulletin board, or whatever. The upgrades might be fixed (obtained in order or by certain material "recipes") or random (to encourage more experimentation when depositing materials).

Yeah, definitely a good material sink, and way for people to compensate not being able to craft 5* stuff.
This is a fantastic idea. The Mag was one of the best MMO helpers I've ever played with. We should get these with the next patch.
I support this all the way man. If pets can't make it in, this is the next best thing.
I think this would be much better than pets. I know that many people like the idea of having miniature versions of monsters or little beasts, but what they are essentially would be extra damage which isn't necessary. I think that like I said, with this being a good material sink, would also be a more balanced way of having "pets". This way they would be a small support role that wouldn't as far as i can see break combat in any way. Providing small buffs seems to be good enough for the role of pets. Overall I think this is a better solution to those players that want pets while still being balanced with the combat.
Glad to see my suggestion is being received well.
Yeah, a material sink was kind of my intent with this. After I posted, I realized that we can have a "collect them all"-type feeling regarding MAGs. When you level one up for, say, a bonus to fire resist and the next gate opens with shock-based enemies, there could be a way to find or buy a new MAG and level it up from a baby into a form that would provide a shock-resist bonus.
One could build up a herd of MAGs and swap them out in towns and Clockworks Terminals like other equipment.
Buying additional MAGs after your first could be done with Crowns or CE, whatever the developers find appropriate.
Or perhaps they could be unlocked through good gameplay. Maybe after you complete so many depths or beat so many bosses (tokens, anyone?) you can buy or unlock a new MAG. Maybe you would get a new "baby" MAG after completing a certain number of achievements. I'm all for bonuses that encourage players to play the game well.
Every u heard of The Pet Idea Well A Mag Can Be A Rare Pet a Pet That U can only get by Recipe After a it is a robot So we could have Both.Just save all this arguin about Pet and mags.Also We can,t Just copy The Idea.
Sice we can not Copy The Idea We Can Make Robot Version of the pets
Yes! Excellent!
They could take up a trinket slot and offer some small bonuses, in line with current trinkets.
I would LOVE for these things to be somehow procedurally generated or whatever -- truly unique to each knight. Maybe some offering similar effects would look wildly different, but a greenish one would probably offer poison resist mainly, etc. They would be mostly "blank" upon birth, with bonuses adding up until some kind of maximum. After that, feeding them would change them a little rather than grow them. Or maybe they could grow forever, with slight minuses on feeding "opposite" mats and an exponentially decaying rate of return, but technically possibly "forever".
I know this kind of thing would be a giant pain to code, art up, and implement, but it would be insanely awesome.

Maybe instead of adding solid stat bonuses, the SKM (spiral knight mag) could act like a single UV in of itself, lower level ones could of course, only provide a low level UV. As you evolve it or get higher * recipes of different classed pets you could eventually build up to at least a medium/high UV.
Also a big draw would be appearance!!!
Are you saying that a UV that the MAG provides would be applied to your gear as an overall buff? I was a bit confused as to your recommendation.
I would say this a good idea to go in the game but are u forgettin lots of people may also want pets instead but i want both to
My thought is that mags would be more realistic. As I posted earlier the players that are in support of pets are really just looking for an extra damage source. They want pets to be able to damage enemies, and this would only make levels easier. I don't think the game needs any mechanics that would make the combat a lot more easy to deal with. MAGs would only provide some type of small buff that wouldn't be breaking the game. I know a lot of players would like to have "pets" but that just wouldn't be necessary.
+1 for MAGs and Guild Hall upgrades through materials/minerals.

This is an awesome idea!
Although we can't call it MAGs because that would be like, copyright infringment. Or something.
Maybe some acronyms?
MLH: Mechanical Little Helpers
ELF: Electronic Little Friend -OR- Electronic Life Form
PSB: Personal Stat Buffer
CAP: Clockwork Assistant Partner
MEA: Mechanically Energized Assistant
Or Just a regular name
Techs
Bots
Jaks
Doks
IDK
Those are just some dumb ideas for names to get the ball rolling.
And Maybe they can Like have special abilities, Like healing one or two pips of health once per level. Or increasing your attack strength slightly in one level per stratum.
Maybe that's a dumb idea...

yeah, I was saying that the mag would give one UV (UV level dependent on mags' stage of evolution) different mag recipes would provide a different UV so people could select mags based on their specific needs.
in #14 you said you don't want them doing damage, but if they attacked what you attack at a fixed rate it might be just as useful and the damage doesn't have to be very significant, maybe just enough to save you one sword swing.
(it would be one or the other for balance issues, unless maybe MAGs were always stuck with a low UV and very low attack damage)
I think these would make great material sinks if that is your intent.