Appendage Lamp




Introduction: Appendage Lamp

About: Conceptual creator in the making

The appendage lamp rises from the floor like a giant tentacle. The electrical wire, wraps around the pole as a parasite, clamping itself tightly, suffocating the tentacle. This lamp is originally designed as a visualisation of my personal stance towards the current state of the (dutch) design field. But it would be a great piece for any occasion where you'd like to add a bit of alienation too. Lets say... Halloween or something. I would not advice this lamp for everyday use, cause this Instructable does not cover details like the body to weight ratio. If you do not have a very heavy foot. It will become top heavy very fast. So much, that the weight of a single light bulb might already be too much, and tip the whole lamp over. Be aware of this as well while bending the rod. By trying to add the end of the rod as close to the center as possible.

The lamp is made in 6 major steps;

  • The (structural) inner rod
  • The fabric
  • The concrete foot
  • The electrical wire
  • and the assembling

In this Instructable I will explain every step in more detail. Explaining what all the steps were and the motivation / desired end goal of these steps. So you can tweak it to comply with your own desired outcome.


This lamp is about 1.9 meter in height. Depending on how you will bend the rod, it might be a bit taller or smaller when you recreate it. The bend is done with a 2.4 meter long iron rod, upholstered with a 2.55 meter long piece of fabric. In total, I used:

  • 2.4m2 Fabric
  • 1.5l PUR foam
  • 2kg Cement
  • 2.4m, 4mm iron rod
  • 1 Bolt
  • 1 Ring
  • 4.5m Electrical wire
  • 1 Light socket
  • 1 Power plug

Since I bought everything new, the costs for this lamp are around 20 euros. Making multiple ones, or adjusting the dimension to a smaller version would reduce these costs drastically. And if you are only a little bit like me. You will most probably already have half of these materials laying around anyhow.

In this Instructable I make use of a hanging mechanism which is not thoroughly documented. But anything which is higher than the lamp can be used. If you have any questions about the project and its required steps, please use the comment section for help.

Lets get started!

Step 1: The (structural) Inner Rod

This step requires a special tool, called a "die". For more information on how the tap a thread using a die. Take a look at this instructable:

Preparing the iron rod

This whole process is pretty straight forward. Using a metal saw, you cut the rod to the desired length. In my case 2.4m. As a rule of thumb you could say that around 25% of the length will be lost when you bend the metal similar to my end-result. I made four of these lamps myself, and this is the average height. If you want to have more curves, you'll lose more length. Use less curves and it will stay longer. Pretty straight forward. If you decide to use a longer or shorter rod. Take in mind that the length of the electrical wire should be around +/- 2.5 the length of the rod. For this lamp I used a 2.4m iron rod and wrapped 4m of electrical wire around it. And this is not enough. I had somewhere in between .5m & 1m of extra length to put the plug on. Which is way to short. Do not underestimate how much length you'll lose when you add more length to your object.

When you have cut the rod to the desired length. You will need to tap 1 side with a matching sized die. I would recommend to tap at least 2cm. Just to be sure. But it really depends on the space you have, underneath the foot. I used 2*3mm plywood. So theoraticly, 6mm would have been enough

Now you have cut the rod to the desired length and added a thread to one side of the rod, you can bend it to the desired shape. Do not worry about any small imperfections. They will be unnoticeable when you put the fabric around it. It is also highly recommended to add a piece of tape or something to the end of the rod. So you won't accidentally poke it through the fabric when you pull it over the rod.

Step 2: Preparing the Fabric

Do not make this project hold you back, cause you don't know how to sew.

Now it gets really interesting! The fabric determines the look of the lamp. So you can go really crazy with this. It does is important to understand that it will need to have some characteristics in order to work for this project. Cause if the fabric will let the foam through it will not work. I do not yet know which types of fabrics work, and which ones won't. But based on my small set of experiments with 8 different types of fabrics I would suggest to look into felt-like fabrics or (fake) leathers. Some woven fabrics worked pretty well, like pantyhose's (denier 80). But some woven fabrics would let all the foam go through. Denim for instance looks great for not letting foam get through. But... Looks can be deceiving. So make sure you make a small sample first. Samples for this are super simple to make, just sew 2 rectangles up on each other with a small opening somewhere. So you can spray the foam inside.

Sample in denim gone wrong

Once you have found a fabric which is suitable for this project. You will need a lot of it. Around 265cm in length, and 90cm in width if you want to re-create the exact same tentacle lamp.

The pattern which I used is shown here. Is slightly cone shaped. Trying to emulate the shape of a tentacle. This shape adds more dynamic to the final form and it provides more surface at the bottom. Which can be exploited to create a wider, and therefor heavier, more stable foot.

I drew the pattern directly onto the fabric, using a measuring tape and a black marker. But you could go all out fancy and cut a paper shape first. Or use a special fabric crayon. Most important is how you draw this shape the most easiest upon any surface. Whether it is on paper or textile. I drew 2 dots, 255cm apart from each other. Then I drew the two outlines on a 90 degrees angle. 8cm on one side, 32cm on the other. Using the 2 dots as the center point. Then using something long and (somewhat) straight to connect the dots together. Then I drew the same shape again. Normally I would just fold the fabric together. But with a pattern of this size. I would simply waste too much fabric.

Then I cut the fabric. If you keep the seam on the outside like I did, it is important to pay attention to the cutting and cut nice straight clean lines. If you want to hide the seams by turning it inside out after sewing. It doesn't really matter how clean you cut them. Now the fabric is cut, you can start sewing. This is a really straight forward process, since it is just 1 big line. Just put the two pieces on top of each other and use some pins to keep them together.

If you want to hide the seams, you must put the faces you want to see in the final result facing each other. If you want to keep the seams on the outside, put the faces you want to hide on the inside facing each other.

Step 3: Pouring the Foot

I will not explain how you should pour and mix concrete in this step. Mikeasaurus has a great workshop on this in much more detail I can ever cover in this Instructable

This step is a tricky one. It is not very difficult but it has two different factors which are related to the dimensions of concrete foot and therefore mold. The outer diameter of the mold and the center diameter. The center diameter equals the diameter of the rod + a tiny margin. I wrapped a piece of tape around a 4mm nail to comply with this extra margin. The outer diameter is related to the outer diameter of the fabric. This might seem complicated to measure, but it is rather simple. 1 Piece of fabric is 32cm in width on the bottom side. When you multiple this by 2 (since we have 2 pieces of fabric). This adds up to 64cm. This value represents the circumference of the concrete cylinder we want to pour. Because using the circumference for creating a circle is not very useful. We want to know the radius or diameter. Using basic maths, or an online calculator we can use the circumference to convert it to a radius or diameter.

circumference = π * diameter

diameter = circumference / π

in this case, the foot for this object needs to have a diameter of ~20.4cm. Because I had access to a laser cutter I made a super simple pattern and cut it out. But if you have not got a lasercutter you can achieve the same result consuming just in a little bit more time. But you can also just go rogue with this step and just use an old bucket. Glue a cap of something to the center. Pour the bucket with concrete and then drill the hole for the rod after the concrete has set. It is all up to you.

Making a custom mold

The pattern consisted of a circle of ~20cm in diameter + a smaller circle of ~5cm in diameter with a smaller circle of 0.42cm in diameter. The 20cm circle is for the foot. The 5cm circle is meant for the gap where the nut can hide in. The 0.42cm circle is the hole in the 5cm circle for the nail to go through. I then laser cut this pattern twice and cut 4 pieces of wood on the same length (slightly shorter then the length of the nail). Which ends up in having the following set of items/parts:

Besides the nail is everything made of wood. Assembling is just done with wood glue & screws. Use the image above as a reference of how the mold should look like. When you have assembled all the parts. The base for the mold is done. Now it needs to be sealed. For this I used a piece of transparent PVC (which just happen to have something printed on it, as you can see in the picture
). I rolled up the piece of PVC and put it inside the frame. To prevent leakage. I used a glue gun to seal the PVC with the wooden frame.

Now the mold is done, you can pour the concrete. The more you pour, the more stable the lamp will be. I advice you to use a minimum of 2.5kg ~10cm in height. But the more you pour, the better the result.

Step 4: Electrical Wire

I will mostly skip this section, cause it is rather straight forward. Just make sure that the chord is long enough. As a rule of thumb I would advice to use a chord 2.5 the length of the iron rod. But you can play with this yourself as well. Maybe you just want to strangle the fabric more than I did or less. Depend on this personal preference you can use more or less chord. In my design, I used a 4m long chord. But I would use 5m for a next time. If you do not feel comfortable with wiring up the lightbulb, I suggest you to take a look at this class:
. This covers all the basics of the process. Which ain't more than you need for this project.

Step 5: Assembly

Now comes the fun part! Assembling the lamp. We start by hanging the iron rod vertically with the tapped thread upwards. I created a special rig for this. A 20.4cm circle with a hole in the center, screwed upon a beam. But you could also just use the concrete foot which you have poured already. Or a bucket with a hole in it. Whatever you do to hang your rod. Make sure it is as vertical as possible. Because if you do not hang it straight, the lamp won't stand straight. This step is critical if you want your lamp not to tip over easily.
When the rod hangs correct and stable. It is time to pull the fabric over it. Pull it first fully over the rod, from the bottom to the top, and make sure everything is in place how you like it. Then, slide the fabric downwards till 1 third of the rod is covered with fabric. It is important to fill the fabric in multiple steps. Cause it will clog up in the center if you foam it in on go. Resulting in an uneven result. Some parts won't have foam at all, while other will be fully hardened.

When you are spraying the foam be careful and make sure the space is well ventilated. It is horrible to clean it up. When you are done foaming, fasten the fabric at the top. So it will cure in the right shape. Do not try to push the foam around inside the fabric by kneading the fabric. This will most likely get the foam through the places where you touched it. It is not super fragile. But it can happen. I have not experienced any issues with winding the electrical wire around the fabric. Do not forget this while the foam is curing. This way the fabric will bend around the chord. Make the wrapping as tight as you like. When the foam is curing, it will wrap around the chord. The tighter you wrap the chord the stronger the effect will be.

After the foam is cured, you redo this step for the second part and after that the third. The last section will most certainly result in a situation, where the foam is coming out from the top. That is great! That means you do not have to worry that the concrete foot won't be big enough. You can now carefully cut away the foam so the concrete foot will be pushed against the foam when you tighten it with the nut (do not forget to put a ring between the concrete and the nut). Also be careful to not cut away to much foam. This will make the lamp wiggle upon the concrete foot.

Do not use straws to extend the tube

I tried to use straws as well to extend the reach of the tube. And while this is partially possible I would not recommend it. If you do not tape it well enough, the straw will be blown of the tube. Causing a huge polyurethane mess. Which is hell to clean up. Also it does not really work very well anyhow, since it does not bend that easily through the foam. It is better to just pull the fabric down.

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    5 Discussions


    1 year ago

    So creepy! I love it and imagine a couple of these would make great Slenderman arms :D

    Penolopy Bulnick
    Penolopy Bulnick

    Reply 1 year ago

    I agree! Fun and creepy lamp!


    1 year ago on Step 5

    Brilliant write up. My laughter will quietly become the glue that lubricates my other imagination.


    1 year ago

    Neat with many possibilities. What spray foam did you use? The stuff in cans from the home center? How many cans?


    Reply 1 year ago

    I used the cheapest spray foam from the home depot I could find. Normally they mention the expansion ratio, but these don't. I used 2.5 cans of 500ml. So between 1 liter and 1.5. If you can find the expansion ratio of your foam. Theoratically you could measure how much you will need. But I have not done that. If you measure to cylindrical content of the sleeve. I use the average of the smaller cylinder and bigger one, which is around 104 liter. This would mean that if I would have used a foam which would expands 1:11. I would only have needed 1 liter.

    I am not sure if this holds up though, more experimentation should be needed in order to give you a thorough answer to this one :-).