by Yun-Han Lin
We spent our first summer this year, after we moved our studio to the mountain. When we stepped outside to the yard, there are countless mosquitoes waiting, so mosquito coils have become a must. Yet, the metal coil holder that came with the coil breaks easily, as it rusts and wears off due to the humidity in the mountain. For this reason, I might as well try make some cement coil holders by myself!
I was thinking about a shape of a hill, so that coil spiral on top of it looks like sunrise from behind a mountain. For the shape of the hill, I used paper cups bought from a store for mold-filling with cement. As for the dent in the middle for the coil, I cut out foam boards in shapes with a laser-cutter as the mold on the inner layer. There was cement in two different colors, where one was white to make it look like there is snow on top of the mountain. After the cement dried, I dug out the foam board from the mold, and voila!
2. First edition
The first edition was made based on the structure we had for the holder, where there were only three layers of foam boards cut into trapezoids that were stacked together, with a small bar put in the dent. The removal of foam boards was labor-intensive, since the dent was small, and there was barely any gap between the boards and the dried cement. I had to remove the boards slowly and piece by piece, without using too much force, because the whole mold may crack from the bottom where the cement layer was thinner. The finished product is a complete coil holder ready to go, and I think it would be nice to send them to the subscribers to our channel. The problem was that according to the requirements for shipping, the package shall not exceed 250g in weight, but this model weighed over 300g. Hence, our goal is to reduce its weight.
3. Second edition
To reduce weight, I added more smaller board pieces, also in the shape of trapezoid, to both sides of the original model. In this way, there was less space to be filled with cement. On the outside, the design looked the same, but the weight should be substantially reduced, since there was not as much cement filled. The rest of the steps were the same, but the removal of the foam boards became even harder, since the added trapezoids complicated the board shapes. After I finished, the weight was reduced, but still a bit shy of the requirement.
4. Third edition
A few adjustments for this version
- To make it easier to remove the added smaller foam boards, I decided to just immerse them into the cement, so that there is no need to remove them.
- There were also small triangles added to the bottom of each piece of foam boards to reduce even more space to be filled with cement.
- At the bottom of the boards, I placed a piece of plastic sheet, so that the liquid cement had as much contact as possible to the boards. It also made it easier for me to remove the paper cup on the outside layer.
- Before filling the cement, I also used demoulding spray to make it easier to remove the paper cup.
5. Materials and tools
- Concrete mix for filling by Lotos (white)
- Concrete pigment by Lotos
- Foam board (5 mm)
- Foam board (1 mm); small bar (same material, 35x10x10 mm)
- Paper cup (9 oz from Carrefour)
- Demoulding spray (YRC 505A Silicone Aerosol)
- Plastic sheet
- Hot melt adhesive
- Containers and stirrers for cement mixing
- Flat-head screwdriver
6. Overview of each version
In fact, if there was no need for delivery with a weight limit, the first edition, with the use of demuolding spray and plastic sheets, turned out good enough. The design for the inner layers was simple. Through photocopy, the design could make a great hands-on project for students and children, where they could cut the foam boards against the copies to get the right shape. As for the third edition, the finished product is light, which meets the shipping requirements. There was also less cement used, which saves materials.