First 500 pre-orders get 100g premium chalk for free
01 — Founder letter · Den Bosch, NL

Hi.

I boulder. I also like having a project going — something to figure out, something that's mine. At some point the project became this: could I make a chalk bag myself?

The reason was simple. I couldn't find one I actually wanted. Everything online was dull, and the things I wanted — magnets that hold, a mesh pocket on the side, a closure that works with one hand — weren't there. So I stopped looking and made one.

— Boudewijn. Den Bosch.
2026Founded
Den BoschNL, EU-first
500First-run units
The founder of MAG BAG topping out a boulder problem on sandstone
The matte black MAG BAG chalk bag, blank and ready to draw on
02 — Why bother

Every other chalk bag is finished.

Grey, brown, a logo you didn't choose. Fine at the wall, boring in your hands. And half of them still close with a drawstring that fights you while you're pumped.

MAG BAG started as a list of complaints: magnets at the top so it doesn't spill, a mesh pocket on the side, brush loops that hold a brush, a bottom you can stand it on. And a surface you can draw on, because if I'm making my own bag it's not going to look like everyone else's.

03 — How it got made

Six samples. Three factories.
One bag.

I talked it through with a friend, then went looking for people online who could turn a list of complaints into a real design. That gave me something I could send to manufacturers in China.

The hard question was the surface. Nobody could tell me what you can actually draw on with chalk and still wipe clean — so I asked three factories to send samples and find out. Six samples later, one of them was right. Everything you're holding is the version that survived.

Early MAG BAG sample, rejected
Sample 01 · rejected
Later MAG BAG sample, closer to the final bag
Sample 03 · closer
The final MAG BAG sample that went into production
Sample 06 · this one
04 — What it turned into

People drew on it before I asked them to.

The first bags went to friends and to the gym. They liked the magnets and the mesh pocket. Then they picked up chalk and started drawing stupid things on each other's bags, and that was the moment MAG BAG stopped being a product I designed.

You spend months on something without knowing if anyone else will care. They did. I ordered 500.

A drawn-on MAG BAG chalk bag in the bouldering gym
Close-up of chalk drawings left by friends on a MAG BAG
05 — What MAG BAG stands for

There's no
other like it.

Blank black surface. You decide what goes on it, you wipe it, you decide again. That isn't a feature — it's the point. Every other chalk bag is already finished when you buy it. This one starts when you pick up the chalk.

Walk into a gym with a MAG BAG and there's no question which one is yours. No logo, no colourway you didn't choose — just whatever you drew. And the next session you can draw something else, or add to it, or start over.

Most gear blends in. A MAG BAG stands out — not because it's loud, but because it's yours.

06 — Manifesto · 7 lines
  1. 01MAG BAG makes one bag.
  2. 02Black. One colour.
  3. 03The chalk is the pen.
  4. 04The bag is the canvas.
  5. 05No two are the same.
  6. 06Brush off. Re-draw. Repeat.
  7. 07Designed in the Netherlands. Shipped from Den Bosch.
07 — FAQ-ish

Things people ask.

Why one colour?

Because the colour is whatever you draw on it.

Will marks come off?

Yes. Brush, damp cloth. Not the washing machine. More on cleaning →

Is chalk included?

The first 500 pre-orders get 100g premium chalk for free so you can start drawing immediately.

More products soon?

No. One bag. Forever.

Can I draw with anything?

Liquid chalk works. Markers don't come off.

What's in the box?

Bag · hangtag · sticker (and 100g chalk for the first 500 pre-orders).

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