what should I put in my pencil pouch?

I carry a Bausch & Lomb Hastings Triplet Magnifier, 14x on a key ring with some other tools (little bitty Streamlight, small Swiss Army knife, Sandisk USB3 64GB thumb, spare key rings, etc.).

I don’t use that magnifier often but when I do, wow, that thing is amazing and really reveals some tiny things with great clarity. It’s something that most people could easily carry their whole lifetime; small, durable and high quality.

I carry a similarly shaped-sized pencil case. In general, I need tools to make marks, cut stuff, and put stuff back together. Therefore I always carry 2 pens, 2 pencils, a pencil sharpener, a sharpie, a white board maker, an xacto handle, a small pack of blades, and bandaids (for tape). When I’m fully loaded I add an awl (with a small cork on the tip), a small pack of brads, and a 6” metal ruler, a small electronics screw driver, a few M3 nuts and bolts, a USB flash drive, a small amount of wire-wrap-wire, a small binder clip, and a pack of Wrigley’s Spearmint Gum. 

Depends on what you want to use those things for. 

If you want things mostly for writing and taking notes, I would add a self-enclosed pencil sharpener, a small ruler, a small single hole punch, an eraser shield if you are really particular, a book makers bone folder for making very precise creases in paper, paper clips, little arrow shaped post-its, a mini stapler, a roll of tape and an eraser that looks like a mechanical pencil except instead of lead pushing out, there is a long thin eraser in it. A pencil extender. It is listed somewhere on this site, for extending the small stubs of pencils so you can use every bit of them.

For drawing and artwork I would add to that, a small rolling ruler which makes quick work of drawing parallel lines, a small french rule for drawing curves, a small architect’s ruler, a brush pen or two in your favorite colors, a water brush: looks like a large pen but has a reservoir in it that holds water. Even if you only do pen or pencil drawings, a single color wash over select areas can really add to them. A tiny watercolor set with a built-in pallet. Somewhere on Cool Tools there is a pair of scissors that folds up into a pen-shaped enclosure. Both a swiveling and a fixed blade craft knife, a small metal ruler and a small piece cut off of a self-healing cutting mat. A high magnification set of reading glasses for detail work. An emery board for sharpening or smoothing things.

If you are looking for everyday carry sorts of things, in addition to Wayne’s suggestions, I would add a lenspen or two for cleaning camera lenses and glasses (mark which one you use for glasses if you take two, skin oils are not really great for camera lenses), an emergency sewing kit and a small first-aid kit containing a few band-aids, antibiotic ointment, interdental brushes or toothpicks, tweezers, hand lotion, eye drops, fingernail cutters and an emery board, throat lozenges, analgesics and antihistamines, breath mints and coffee candies for those meetings or classes you can’t stay awake in.

If you do repair or creation work, I would take a few precision screwdrivers (my favorite are Wiha), a spudger for opening cases and gently prying off electronic connectors and a sharpened putty knife for opening cases. 

Oh yeah, and while I was looking up what the names of some of these items are, I came across this which might be a good addition for makers: a ”striking knife” for marking lines to cut on wood. They say it will give layout lines one tenth as wide as a pencil and therefore more accurate: https://www.amazon.com/dp/B0056P4Y8I/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&colid=3TV0Q892V738E&coliid=I18VHW4WRHIQZE

I agree with an awl or perhaps an ice pick. They have many uses.

I have a very similar pouch in my bag, and in it I carry: 
- A good mechanical pencil (as a backup to the one in my pocket.) I like the Paper Mate ClearPoint in 0.5 mm. 
- A decent pen (as a backup to the one in my pocket.) I like the Pilot Varsity disposable fountain pen, blue ink, medium point. They are cheap, smooth, and with the right bit of hacking, refillable. I also include a Uni-ball Jetstream, blue, fine point. The Jetstream is a pigment-based rollerball. It never skips, it doesn’t smear (so it is great for lefties), it doesn’t fade or wash away. It is also very smooth. The Varsity is great, but the ink is water-soluble.
- A Sharpie, in case I need a permanent felt-tip pen, which happens surprisingly often. Sometimes I include a silver ink Sharpie, which will be legible on almost any material. 
- A small, disposable snap-off knife with locking blade. They cost perhaps a dollar at Home Depot. The blade is very thin and very sharp. The lock makes it safe and versatile. 
- A spare USB charger, plus a short cable. Because I lose these kind of often, and sometimes you absolutely have to have one. 
- If I happen to be teaching that term, a spare Dry-Erase marker. 
- A few binder clips.
- A pad of small Post-It notes (for notes to myself, bookmarks, etc.) 

A pencil-case habit dating back to my design-school days: a surgical scalpel with some scalpel blades (mostly shape #24). Scalpels are nicer than snap-off retractable knives for cutting paper because you don’t have to cut with the tip so the curved blade cuts better and doesn’t dull as quickly, while for those cuts that are better done with the tip, the tip is finer and sharper. (Though retractable cutters are more convenient when getting out or putting away – it’s not quite that quick to add/remove the scalpel blade)

A junky disposable scalpel handle might come with the blades, but since I use these long-term instead of throwing them away it\'s worth paying a few dollars for better; one of these has been serving me well for over 20 years now.

Your pencil case is a very close (almost identical) relative of a high-quality microphone case, such as the one that came with my Neumann KMR-81i boom (short shotgun) microphone. There’s a lot of audio gear that matches this form-factor, although with microphones you need to make sure the length works with the case. A classy case that’s worthy of the value of pro- audio equipment gets extra points for the crew on any set where I’m directing.

One item i keep in my pocket and pouch is the end of a roll of electrical tape.  If you peel the cardboard roll out of the inside it can be squashed flat enough to fit in a coin pocket or wallet or tool pouch and it occupies very little space but is there to taoe a finger or coil of cord or a damaged electrical cord. When you take it out and unsquish it the cardboard remnants let it slide around your finger easily. Full rolls can be done this way to take up less room in a toolbox or pack. The same works for duct tape if you roll some around a drinking straw to go camping. Make several small rolls at once and then slice the straw up to put  one in yiur backpack and another in the car. If you step on the roll it will flatten so it won’t roll out of reach if you drop it as well as saving space.

One item i keep in my pocket and pouch is the end of a roll of electrical tape.  If you peel the cardboard roll out of the inside it can be squashed flat enough to fit in a coin pocket or wallet or tool pouch and it occupies very little space but is there to taoe a finger or coil of cord or a damaged electrical cord. When you take it out and unsquish it the cardboard remnants let it slide around your finger easily. Full rolls can be done this way to take up less room in a toolbox or pack. The same works for duct tape if you roll some around a drinking straw to go camping. Make several small rolls at once and then slice the straw up to put  one in your backpack and another in the car. If you step on the roll it will flatten so it won’t roll out of reach if you drop it as well as saving space.