DIY Ultralight cooking tray

Submitted by Thorsten on 8th March 2022

Nothing much has been happening for us in the past two years in terms of advancing our Polar ambitions. However, there is finally light at the end of the tunnel: it looks like we’re finally set to go to Norway for some easy camping and skiing on Hardangervidda at the beginning of April. So it’s time to dust off and inspect our kit and to revisit a project I started two years ago, but then never actually tackled: building a better cooking tray for us.

‘Better’ in that sentence can be directly translated to ‘lighter’ since the functionality of a cooking tray is quite limited, but before I dive into the details, let’s start with what a cooking tray is and why you would want one.

Why have a cooking tray?

Your stove is one of your most important pieces of gear on a Polar expedition. Without it, you won’t be able to obtain hot water by melting snow. There’s a multitude of trekking stoves out there to choose from, most of which are gas-powered. Some of those, like the Jetboil or similar systems, do a great job of packing all the components into a single unit that is easily portable. Sadly, gas-powered stoves tend to malfunction at temperatures we might encounter on a Polar expedition, so almost everyone used fluid fuel stoves for our purpose. Those setups are usually a bit bulkier. They consist of the stove itself, a fuel hose, a fuel pump and a fuel supply – usually a fuel bottle. That isn’t at all bad, however, because it makes the individual components easy to maintain, repair and replace. Petrol stoves are also trickier to light, and even if you’re careful, they might produce a sudden flame when the fuel ignites, so you want to keep them away from your tent as far as possible during ignition. We usually light the stove at the bottom of our kitchen dug-out and move it to the ‘cooking shelf’ once the flame is stable. Sadly, you will not be able to move your stove around easily with a fuel bottle dangling off the side of it, and that’s where the cooking tray comes into play. It allows us to strap all the components to a surface and makes it easy to move around in the tent. Additionally, mounting the stove on a flat surface prevents it from sinking into the snow and spilling your precious warm water.

The Mission

Our current cooking tray is simply a plastic cafeteria tray with some basic fittings. On its own, it weighs around 400g. A lot of explorers use similar setups with plastic trays or wooden boards. So far, I have not seen a commercial solution for Polar cooking trays (apart from the high-tech one by Thomas Ulrich, which is insanely expensive), so everyone uses their DIY trays anyways. It always struck me as an area where obvious weight-optimisations are possible, so I wanted to see how well I can do.

My mission was to create a cooking tray that …

  • …is as light as possible.
  • …has fittings for an MSR XGK Ex stove and a fuel bottle.
  • …is sturdy enough, so the setup can be moved when gripping the tray with one hand.
  • …is easy to repair in the field, should anything break.
  • …is affordable (aka, I want to be able to justify the expense over just using the cafeteria tray).
  • …can be built without specialised tools.

Looking for the base Material

So roughly speaking, the cooking tray has two sets of components: the base and the fittings. Most of the 400g weight of our original tray comes from the base, so this is where I started looking for weight-savers. There are two angles to explore, reducing the area required and using a lighter material. The area required is determined by the layout of your stove and fuel bottle. With a bit of experimentation, I decided that I would likely need an area of 20x35cm to make everything fit. The fuel bottle does not need to be completely covered by the tray, it is perfectly fine that it sticks out a bit.

With that out of the way, I started researching the best material. Titanium, aluminium, glass fibre and carbon are all obvious candidates for stiff and light materials. Of those, carbon fibre is usually recommended as the lightest choice, but it is not very easy to work with. You need special blades to cut it and I don’t have those. You can drill holes into it with a normal metal drill, however, as long as you use a drill with 2000rpm or more. So I came up with a plan for the fittings that would only require me to find a sheet with the right dimensions and drill a few holes into it. My only remaining question was how thick the sheet needs to be to carry the weight of the bottle and the stove. It is surprisingly hard to find descriptions, pictures or videos of carbon sheets in use on the internet, so in the end, I settled for the brute force method: I just ordered three sheets with different thicknesses (0.5mm, 1mm and 1.5mm) and would return the two I don’t need. Turns out the 0.5mm is clearly too wobbly, while the 1mm seemed just sturdy enough. The 1.5mm is definitely good enough, but each 0.5mm of thickness adds about 50g of base weight to the tray, so I decided to try it with the 1mm sheet and see how that goes.

Assembly

My first step was drilling the holes for my fittings into the carbon sheet. You can see the layout in the picture.

I decided I want one hole in each corner, so I could add little rubber feet to the tray. Those will serve a dual-purpose. They raise the tray from flat surfaces and create room for the fittings to stick out the bottom. And they sink into a softer snow surface and act as snow-spikes, hopefully preventing the sheet from sliding around. The top left hole is used to fit one leg of the stove as well, while I need to drill holes for the other two legs separately. Those will also create rubber feet, so all three legs of the stove have the same level of support. To fit the fuel bottle, I also need two sets of two holes each. I drilled the holes with the protective plastic still on, so I could easily mark it with a sharpie and it would create cleaner holes. With the drilling done, I could install the bolts in the corner and the fittings for the stove.

I decided the easiest way to fix the stove would be a nut on top of the bolts I already had in place. I am using a plastic one that is easy to tighten by hand.

That leaves only the bottle fittings to do. I decided to go with two silicone straps to keep the bottle in place. We used bungee cords on our first attempt, but the fuel bottle is so smooth, it easily slides around unter the cords, especially when you push it, like you do when pumping. I hope that rubber straps will grip it more easily and keep it from moving around. I bought a set of Sea-to-Summit Stretch-Loc straps and fixed them to the board using cable ties.

And that’s it, our new cooking tray is done. It turned out to be a surprisingly simple construction in the end. On the side of the fuel bottle, there is a noticable bend when the bottle is fixed. I don’t think that will be a problem, since the main pressure from the heavy pot will come down on the side of the stove. Should it turn out too bendy, I can still do the same build with a 1.5mm sheet, which will add 50g to the total weight. The whole thing weighs 149g and thus saves us a whopping 250g of weight from our old setup. Not too bad in a world where people cut their toothbrushes in half and the labels out of their clothes. I spent about 50 quid on the materials I used in the final product, so I’d say it’s fairly affordable. But please don’t ask me how much I wasted on unsuccesful attempts (not chronicled in this blog post).

To summarise: our new cooking tray

  • Weighs 149g
  • Cost about 50€
    • 35€ for a carbon fibre sheet
    •  under 5€ for screws, bolts and other materials used for the fittings
    • 11.99€ for silicone straps used for bottle fittings

Full list of materials and tools I needed to build this

  • Carbon sheet 1mm 20x30cm (or 1.5mm if you want to make sure it carries larger weights)
  • Metal drills 2mm (for pre-drilling) and 5mm and power drill with >2000rpm
  • 6x rubber cap for bolt/nut
  • 6x M5 nut
  • 3x M5 bolt 12mm
  • 3x M5 bolt 20mm
  • 3x M5 plastic wing nuts
  • 2x cable ties
  • 2x Sea-to-Summit Stretch-Loc
DIY Ultralight cooking tray

Thorsten

Keen hiker and ÖAV trekking and hiking guide, in love with Nansen. Owner of the most walk-averse rescue dog ever. Ice cream lover, kit junkie, runner and mad software genius.