Character Storage Capacity

It appears that the belt slots can hold 7 of one item and start with 3 'slots'. How does one expand the number of belt slots?
In the Inventory list, what is the maximum number of each item that can be stored? Fractured sparks never seems to climb beyond 35 ... am I just not finding any more in the Arcade missions (I'm an Apprentice 2-2 atm).
I was not able to find this info in the wiki.
Thanks in advance

By "Belt Slots' I mean the buckets where vials, health pills, fire barriers and other mission drops get sucked up into. One is reserved for the stamina cube and the rest never seem to be enough for all the drop types that come. I understand that depending on the creatures in the level, certain combat types are the only ones you would practically need, but I'm a packrat and I hate not keeping everything :-)

Yeah, my bad. You can't expand those. The first three are your sprite's skills, and the last four are your items. You can only put 1 of each item in each slot, and they only stack up to 3. There's no way to expand this.

Thank you Dibsville, for the clarification.
So, I know there are plenty of players who have played for years and would know if there is a limit.
Maximum of each Material?
Maximum number of weapons (assuming one of each possible variety)?
If it is unlimited in all cases, then am I to assume Guild Storage is only for the sharing of the gear between members (i.e. the convenience of transferring goods)?
Sorry to seem like I'm adding to this, but I'd like to craft as many types of weapons as I can just for a goal.

There does not appear to be any maximum to your inventory. For example, you can have thousands of Soul Dusts and dozens of swords.
Guild Storage exists to help guilds foster a sense of community, by having knights with extra equipment give it away to guildmates without much equipment.

inb4 someone rage crafts Brandishes in an attempt to find a limit.

Remember to change your controls when you need/want to :)
Sparks of Life can go well beyond 35, you just need to be lucky enough to get a drop, as seen here: http://i.imgur.com/RpqxFpY.png
EDIT: ignore what I put here the first time.
You can't expand your slots.