Like a medical kit you keep back in your car, the Magical Emergency Kit (or MEKit, for short) should be stocked with things that you consider essential for your practices. Most aren't going to be able to fit three wands, two knives, a bowl, and a bunch of candles into their back pocket, so you'll want to pick and choose from your options and pick the more sensible necessities.
You'll need to decide how big this is going to be. The one I'll be talking about here will fit into an Altoid's can. Its not high tech, but its effective.
According to measurements I found online, an Altoid's tin is 3.9" long, 2.45" deep and .875" tall. This means you can fit the following in it:
- 5 birthday candles
- 6" of twine
- Sigil paper (I recommend flash paper for this, but even small sticky notes'll do)
- A small pen
- Incense matches
- Small Swiss Army Knife
- A small pen (Fisher Space Pen, like the X Bullet model, will work)
- A nail or three
- A 1/4 dram bottle of holy water, florida water, or anointing oil of your choice
- A packet of salt
- A packet of sugar
This is a small enough kit to fit into your back pocket, but there's enough in there to take care of any particularly urgent situation on the go. ;)
Of course, you're welcome to ponder and come up with your own ideas here.
Be well & safe travels.