Telescopic Star Projector




Introduction: Telescopic Star Projector

About: Justin Tyler Tate is an artist, designer, animator, teacher, jeweler and maker/hacker who produces with thoughts of culture, science and interactivity.

It's so great to sleep under the stars but how often do we really get a chance to do it? I know most of MY time is spent in the city and living pretty far north so that even in the summer you don't really want to sleep completely exposed. BUT, you can make this Telescopic Star Projector using some common materials and some super bright LEDs...and what's best is that you will be expand/contract the projection so that you your star projections will fit on most ceilings.

This is the fourth version of the project, after a some less-than-ideal attempts, and probably it could use some tweaking so if you build one and think of any alterations that can be made, please suggest them.

This project is suitable for kids and adults alike. Let's get started!

Step 1: What You Will Need:


  • An x-acto knife or scalpel or utility knife (a.k.a: box-cutter, carpet knife, razor blade knife, razor knife, pen knife, stationery knife, sheetrock knife, or drywall knife...and I have also heard them referred to as an "airplane key")
  • A ruler and or measuring tool
  • A straight edge for cutting against
  • A b/w printer
  • A needle


  • Foamcore/cardboard (1/2cm thick)
  • A super bright LED (I used this IKEA JANSJÖ flexible reading lamp)
  • Aluminium foil
  • Tape and/or hot glue
  • Spray adhesive (alternatively you can use tape or hot glue but spray adhesive will achieve the best results)

*You could also make this project out of wood but the cut-lists are based on material that is 1/2 centimeter thick so either you will have to use wood that is 1/2 centimeter thick or you will have to amend the cut-lists to accommodate the thickness of your material.

Step 2: Zoom Box, Part 1

We'll start with the inside of the zoom box which will hold your super-bright LED light and, by moving it in and out of your Telescopic Star Projector, it will allow you to enlarge or contract the star map on your ceiling.

- You will need to cut the following pieces out of cardboard or foamcore:

  • 2x 25.0cm by 18.5cm
  • 2x 25.0cm by 10.0cm
  • 1x 18.5cm by 09.0cm
  1. Start by cutting all of your pieces.
  2. Tape them together on one side, leaving 1/2cm of space between each, alternating between the wide and narrow pieces so that you make one long strip that is 25cm tall by 58.5cm long (including the gaps).
  3. Cut a piece of aluminum foil which is big enough to cover all of them.
  4. Spray the pieces of foamcore/cardboard with spray adhesive ON ONE SIDE.
  5. Neatly press the piece of aluminum foil onto the foamcore/cardboard on the side that you just sprayed with adhesive. Make sure that you are always gluing the matte side of the aluminum foil because you want to use the shiny side to reflect light.
  6. Trim off any excess aluminum foil around the edges of the foamcore/cardboard and cut it between the gaps.
  7. Glue the pieces together to make the walls of your zoom box so that the aluminum foil is on the inside and the narrow pieces of foamcore/cardboard create the edge of the box by sandwiching the wider pieces.

Step 3: Zoom Box, Part 2

  1. Spray the bottom piece of your zoom box with spray adhesive and press a piece of aluminium foil, just bigger than the bottom piece, onto it. Trim off any excess foil.
  2. Cut a circle out of the center of your bottom piece, big enough for your super-bright LED light/bulb to fit into.
  3. Secure your super bright LED light/bulb into the hole

Step 4: Outer (space) Box

This step is pretty straight forward; we will be making a box that fits around our zoom box.

- You will need 4 pieces of foamcore/cardboard that are cut to the following dimensions:

  • 2x 30.0cm by 21.0cm
  • 2x 30.0cm by 10.0cm

*Note: You can attach aluminum foil onto the pieces you just cut but I feel that it could get scraped off when you move the zoom box in and out of the outer box.

- You can build this outer box directly over top of your zoom box. They should fit together snugly so that when you pull the zoom box in and out, it should stay in place just by its own friction. In the zoom box, the narrower pieces overlapped the wider pieces but for this outer box, that situation is reversed. So you will need to glue the wider pieces so that they overlap and sandwich the narrower pieces.

Now you should have a zoom box which fits into your outer box.

Step 5: Trapezoidal Prism Projector

- Cut out the following rectangles:

  • 2x 30.0cm by 21.0cm
  • 2x 10.0cm by 21.0cm

- With the two largest rectangles, measure 10.0cm from each edge on one of their long sides and mark those points.

- Use your ruler to draw a straight line between those two points and the corners on the opposite long side.

- Turn your two large rectangles into a trapezoid by cutting on the marks you just made which should leave you with a total of 4 spare right triangles measuring 10.0cm by 21.0cm.

- Use spray adhesive to glue aluminium foil to one plane on each of the pieces and trim off any excess foil.

- Use hot glue and/or tape to join your two trapezoids and your two rectangles to form a Trapezoidal Prism.

Step 6: Lens

Now, it is time to make the "lens".

You will need to make two arches with long sides measuring 30.0cm which will allow them to be attached to your trapezoidal prism projector.

*The images for this step should clearly illustrate the process but I will also describe them:

- Measure out 30cm straight line on your foamcore or cardboard and cut a piece of string to the same length (represented in the images as the line which connects A to B).

-Find the center-point of the 30cm line on your foamcore/cardboard and draw a 15cm long line at a 90-degree angle from that center point (represented by point C in the images).

-Now find the center of your string and while holding its center-point to point C, stretch each end of the string so that it touches the line connecting A and B while being as taught as possible. Mark the two points that the ends of your string touches. We will call these new points, 1 and 2.

- Use a tack, pin or tape to secure the string to points one and two.

-Now with the string secured to points 1 and 2, you should be able to slide your pencil along the inside of the rope between points A, B and C in order to draw your desired arch. By keeping the string taught, you can draw a line on the board to mark your arch and the string will self adjust to keep the appropriate distance from the center point.

- Cut out your arch and then use it as a stencil to trace another exactly like it, then cut out the second arch as well.

- Use spray adhesive to glue aluminium foil to one side of each of your arches.

Step 7: Connect the Pieces

- Use hot glue to connect your Lens pieces to your Trapezoidal Prism Projector to your Outer box. If you measured everything correctly, everything should fit together just right.

- You can use a 2cm wide piece of foamcore/cardboard to strengthen the joints where each section attaches to the other.

- Cut 4 pieces which can bridge the gap between your two lens arches. Wrap them in aluminum foil and glue them into place; two on the edges; helping to secure the Lens pieces to the Trapezoidal Prism Projector and two others which divide the arch into 3rds (see the image above if this is not a helpful explanation).

Step 8: Print & Poke

-Print the PDF attached to this step which is a map of all of the visible stars that can be seen from earth. The PDF is 3 pages long so you will have to print all three pages and tape them together. They have registrations marks that look like || and ||| which need to be aligned in order for the map to be accurate. You can also look for specific constellations or sections of the sky to print.

- Use spray adhesive on the back of the printouts to glue aluminum foil to them.

- Poke holes in each of the black dots, representing stars. The finer the point you use, the more focused the star will be. I suggest using a sewing needle in a set of vice grips but any pin will do.

- Tape your map over the lens section of your Telescopic Star Projector so that the foil is on the inside. Tape and/or fold any excess paper over the edges of the lens to keep light from escaping through seams.

* On the attached map of the visible stars, closer stars are bigger and stars that are farther away are smaller.

Step 9: Visible Stars

Now you have your very own Telescopic Star Projector to blast your ceiling with an imitation night sky! AND with the zooming feature you can make the stars smaller or larger depending on the size of your ceiling.

I hope you enjoyed this instructable and if you have any questions, comments, suggestions or reviews then I would be happy to hear them. Thanks so much!

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    3 Discussions


    1 year ago

    Pretty Cool! It looks like it looks pretty cool.


    3 years ago

    This Instructable is perfect for not only showing kids the stars on the classroom wall/ceilings but also a great way of getting them involved in building the projector. Great instructable.

    Justin Tyler Tate
    Justin Tyler Tate

    Reply 3 years ago

    Thanks for your comment Jon! I hope someone will find this Instructable useful, especially for a classroom project.