Flat Folding Headlamp Diffuser/lantern

Make your own ultralight, cheap-as-chips headlight diffuser/lantern.

As a key design feature, this diffuser folds flat, so you can pack it away in your backpack or pannier and it won’t take up a lot of space.

This tiny project will extend the use of your camping headlight into a surprisingly effective and powerful lantern when camping, or for your emergency box at home.

What you will need

1. A single 2 litre milk carton (HDPE plastic), washed clean
2. Printed template on A4 paper
3. knife or scissors
4. Hard edge or ruler
5. permanent marker
6. isopropyl alcohol

Optional

1. Stapler
2. small binder clip

The idea came about on a recent moto-camping trip, where I had forgotten to pack my camping lantern.

Snuggled up in the dark in my sleeping bag that evening, a web search tempted me with expensive brand name translucent stuff sacks, and M3G’s Instructable for a Flat-Pack Lantern Attachment for Any Headlamp.

I decided my design had to;

1. use simple materials most people have access to or could acquire,
2. was one-piece, that could fold/unfold to insert your light,
3. that could sit stable on a surface, & use your existing headlamp’s straps to hang,
4. the ability to operate the light without removing it from the lantern,
5. was lightweight and sturdy,
6. gave the satisfaction of creating something useful from waste.

Exploring with everyday objects most people have at home led to experimenting with reclaimed milk bottles, with the template refined over time.

While this version suggests stapling and a binder clip, it can still function without.

While this example uses a NiteCore XU25 with 400 lumens, I have found even the 60 lumen Low setting is easily bright enough to light a campsite, including the Red LED function.

In the case of a power outage at home, this easily lights several rooms when hung from a central doorway.

I have also used this with other light sources such as a mobile phone (inverted) with a rubber band holding it on, a strand of LED lights off a USB powerbank, and even a low watt solar garden stake.

The template is 1:1 when printed on an A4 page.

You will have plenty of working material with this design if you are careful with placement.

1. Print and cut 1 cm around the margins of the template.
2. Temporarily place your template on the bottle in the best position, and tape in place.
3. Leaving yourself as much flat plastic as possible, remove the handle, top, and base, before cutting the remaining tube so it is flat.
4. When flat, use the handle of your scissors to burnish and flatten any bends or gutters. Try not to introduce any new bends at this stage.
5. Tape down your template to your working surface, and then tape your plastic flat over the top. Trace your design with permanent marker. You will clean this up later.
6. Cut your template in the HDPE plastic with scissors or a knife.

Take extra care cutting the two half-moon tabs, and undercut the width of matching slots until final assembly in case you need to make adjustments.

1. Invert your plastic, and with a hard edge or ruler, bend and burnish each fold with your scissors handle or the back of your knife. Each bend will be up from the work surface, except for the rounded (a) tabs at the bottom which are best to save for last.
2. I recommend when all bends are made you bend them back and forth to set the bend. HDPE is quite resilient, so you can do this multiple times.
3. Use a hole punch or knife to cut the two binder clip holes at the top of the lantern.

When you have cut your lantern and all folds are in place, remove all permanent marker with isopropyl alcohol and a rag.

1. Fold your lantern into position and push the half-moon tabs into the matching slots.

The tab with the half-moons goes on the outside and the tabs lock against the edge.

Adjust the slots with a knife as needed. Staples can be added to hold if needed.

1. Place your lantern on the table with the base upwards, fold in all tabs with the rounded tabs pointing upwards.
2. In turn, fold so each (a) tab sits over the top of a (b) tab, and staple.
3. Repeat the other side, and the base is done.

To test the base folds flat, squeeze opposite corners and the tabs will fold up into the lantern. Adjust the tab layers to fold and open freely.

Invert, fold in the top tabs so they sit level and your assembly is complete.

Unfold and sit your lantern flat. Fold the top tabs level.

Insert your light and pull the tabs over the back of the headlight.

The shallow points will lock into the back of the headlight.

You can use the binder clip to lock the light in place if needed.

To pack away, remove the binder and headlamp, fold flat, and use the binder clip to hold flat.

A rubber band may also be used.

It feels good to use something you made yourself!

One tiny word of caution, because these are so light and pack so small, you might be tempted to make and take a couple of extra ones as an inevitable giveaway when people ask where you bought the light from.

I hope you have as much fun making these as I did, and I hope to see your photos!