Small items
A small item is something that could fit in a pocket, pouch, or boot with room to spare. Small items do not contribute to your load. Track them on the right side of your Inventory insert, in the "Small items" section.
When you Outfit, you can mark a number of small items equal to 4 plus Stonetop's current Prosperity (+0 by default). If you want more small items, then bring $\diamondsuit$ supplies.
If you acquire a new small item on an expedition, add it to your Inventory in one of the blanks in the Small items section. There's no hard limit to the number of small items you can carry, but be reasonable. If you start stockpiling, the GM might say that your small items count as $\mathscr{C}$ or even $\mathscr{C}$ in aggregate.
When you Outfitted for your trip to the Ruined Tower, you marked 4 small items (because Stonetop's Prosperity is currently +0).
As you explored the upper levels, you found a jagged shard of makerglass, sharp as anything and impossible to break. It's not much bigger than a coin, a small item. You pack it into your tinderbox, and add "" makerglass shard" to your Inventory insert.