Concrete Cathedral Night Light

I have always admired the Gothic Cathedral and architecture in the renaissance age. a lot of the buildings were constructed with bricks and stones and they are still dominating the city skyline of some of the famous European cities. When my wife and I traveled to Italy last winter to visit the famous landmarks, we were both amazed by the craftsmanship and the durability of those ancient structures. I made this miniature night lamp, that can be placed on the floor or in a bookshelf. the ambient light brings a warm and mysterious light into the study or sitting area. concrete is a very durable material, it is relatively easy to work with. and the aesthetic of the rough concrete finishes somewhat resemble the ruins of the ancient building. the build is a weekend-long fun project that is easy to make and uses only a few kilos of concrete. Let's begin! and let me explain the process.

Supplies

1. Pre-Mixed concrete. 20kg bag or less. I used a high strength MPA55 mix. I was going for the ruined/rough finish so this mix has a high content of coarse aggregate. any other type of cement is fine.

2. EVA foam 2.5-3mm thick.

3.scrap wood to make the formwork

4.LED strip- I use in combination with a dimmable switch so the brightness can be adjusted

5.Heavy Cardstock 260gsm, (scrap brochure from real estate agency)

6.Spray Paint or any other paint.

7.Tinted Acrylic sheet 3mm thick

8.contact rubber cement/ hot glue/ instant glue

Step 1: Design Phase

at first, I was thinking about creating a 3d model first to help me visualize the object. Then I was thinking none of the cathedrals built in the medieval age was using 3d modeling technique and they were marvelous. I simplified the design to have just a long stain glass window finish as the light source with a rectangular box shape, small enough to fit in my IKEA bookcase. The design drawing is done entirely in AutoCAD. with a few simple line offset. the arch is an equilateral arch of the shape that is commonly used in gothic architecture.

the White lights are concrete contour, the yellow one is the center light source that will be made of acrylic sheet and paper

Overall Dimension 275mm x 90mm x 75mm(Depth)

I printed a few copies on card stock and ready for cutting the EVA foam sheet

Step 2: Making the EVA Negative Shape

Once I cut all the layers of the contour line into individual pieces I can then trace the shape onto EVA foam and cut them to the exact same size, there are 10 pieces in total each with a 2mm offset. the center cavity is around 40mm wide.

The first Layer I sandwiched 3 layers of the EVA foam together to give it an 8mm+/- depth then the rest is only one sheet thick about 3mm. To make the cavity for the LED light strip, I stuck a piece of styrofoam about 30mm thick. wrapped with masking tape so it will be easier to take out after pouring the concrete.

I used rubber cement to glue the EVA foam. DO NOT use rubber cement to glue polystyrene foam , it will melt it and give off nasty fumes. use double side tape

Step 3: Making Formwork and Pour Concrete!

Once the EVA foam is all glued together I glued a piece of PVA sheet, scrap from old file sleeve. cut exactly to the size of the box so the concrete will be much easier to release from the bottom.

Stick a piece of tube for the wire to pass.

I found a few pieces of scrap in the garage and used hot glue to glue them together. Once the concrete is poured moisture will be drawn into the wood and when concrete is set it will be very easy to remove the glue and the wood board. the wood can be cleaned and dried and use again.

Quickly made a mixing palette. Mixed the concrete as instruction and poured in the mold. I covered roughly 15mm on top of the foam form.

shake it thoroughly to get rid of the air bubble and smooth the top, and wait until it is cured.

Step 4: Curing Concrete

After a few hours. the Top will be hard to touch I removed the 4 sides and the tube, at this stage the concrete is still workable with a palette knife if there is any big hole or unevenness now is the time to fix.

The next day I bake the concrete in the sun for a few more hours. the color is evenly tightened.

now is the time to remove the foam!

Step 5: Remove Foam

peel the PVC Sheet to take out the EVA foam. it was very easy to remove. no mess or break. take out the polystyrene foam was quite easy as well. the masking take helped release the foam and kept it as a whole without breaking.

bake the inside under the sun for a few hours. till the color of the concrete is light, remove any sharp edge with sandpaper.

Step 6: Make Light Panel

I print out the template on a piece of cardstock then using a spray adhesive glued 4 pieces of cardstock together to make it thick.

Cut out the panel frame and glue them together. I spray painted the whole thing with hammer finish paint to give it an antique finish.

I used an orange hue transparent acrylic sheet for the light panel. the LED light I am using is 5600k color temperature the orange will make the light a warm glow. cut it using a bandsaw, to make it more of a frosted finish. I stick a piece of translucent tracing paper on top. the paper diffuses the light more, make it softer, and comfortable to look at.

Step 7: Install the LED Strip and Light Panel Fixture

Make sure the acrylic sheet fits tightly into the recess of the concrete form. stick the LED strip onto a piece of paper and glue it on to the concrete. to reflect more of the light. I lined the inside with aluminum foil as a light reflector. stick a piece of soft material on the bottom of the concrete for surface protection.

At last, Press the light panel into the recess of the concrete. it should be fit in place without using any adhesive.

Step 8: Complete!

Turn on the LED and it is done! good for any indoor space. on a bookshelf as a book stopper or in a hallway corner as a night light. great for a desktop accent light as well.

Enjoy!