Q&A for How to Build a Projector Out of Cardboard

Open the box and put the phone into it; shoe boxes provide easy access.

Make sure that the brightness on your phone is all the way up. Paint the inside of the box black or cover the inside with black paper. If this doesn't help, try using glass cleaner or nail polish remover on the lens.

You let it lean against the box or get something to hold it up, like a stand.

It doesn't matter what size you use, you would just have to cut the hole bigger or smaller depending on the size of the magnifying glass.

Turn up the brightness on your phone as bright as it can go.

They should be at opposite ends of the box. Make sure to turn your screen upside down, because of light rays bending it.

It doesn't matter what power it is.

No, you will need to use a glass magnifying glass for this.

Yes. You should set your phone really bright and color the inside of the box black.

You should get a box that is bigger than your phone so the phone has a bit more space.

They are very inexpensive. For a couple dollars, you could get a decent one to project the image clearly.

You can order one online. Or, if you have an old projector that does not work, you can take the clear glass out of that and use it as well.

We have to paint it black to avoid any unwanted reflections of light rays. Black absorbs all wavelengths of light and does not reflect any unwanted colours.