Placing any two convex lenses (with different focal lengths) a distance apart will create an up-side-down magnified image of far away objects.

These are instructions on how to make a simple telescope out of everyday parts (PVC pipe / magnifying lenses) using specialized 3D printed fittings to hold your lenses in just the right place

Step 1: Assemble Materials

What You Need:

2" PVC Pipe (about 6-12 inches)
Magnifying lenses of different focal lengths (like these http://amzn.com/B003BHW5GQ)
Access to a 3D printer and these files

Step 2: Determine Focal Lengths, Determine Pipe Length

The lenses want to be situated in the telescope the sum of their focal lengths apart. In other words if the focal length of one lens is 6" and the other is 4" then they want to be 10" apart in the telescope

The 3d printed fittings won't be long enough so you'll need a length of PVC pipe to make up the difference.

While there are a number of ways to determine the focal length of your lenses, and calculate what length of pipe you will need, the easiest way to figure it out is to just line up the lenses and look through them both, adjusting the distance between them until you see a clear magnified image of something across the room - no calculator required.

Take note of about how far apart the lenses are. In my example its about 10" (even though the picture shows a different measurement - I was experimenting with a different set of lenses)

The lenses want to be 10" appart, each fitting is about 4" so an additional 2" of PVC pipe is needed plus we want the pipe to engage the fittings by about an inch on each side and leave room for adjustment, I've made this example pipe 4.5" long

Step 3: Dismantle Your Magnifying Lenses

An inexpensive magnifying lens should come apart easily.

The metal ones come apart the easiest, plastic one may have to be broken apart.

Step 4: Design a Fitting.... or Just Download This One.

You can design your own fittings to work with whatever size pipe and lenses you want, but if you're content to use 2" PVC, and the lenses I've pointed you to, most of the work is done. The file can be downloaded on Thingiverse!.

http://www.thingiverse.com/thing:1052256

Step 5: Print the Fittings

The biggest fitting is about 3.25" x 3.25" x 4.5"

You'll need a 3D printer that has a print volume of at least that (most do).

Step 6: Press Lenses Into Place

At this point you've probably been handling the lenses a bit, clean them (especially the inside side) before you press them into the fittings. If they are a little hard to press in, cover them with something padded and tap them in with something heavy like a block of wood

Step 7: Repeat for Second Lens

Step 8: Press Fittings Onto PVC Pipe and Focus

The back fitting has a shoulder in that the PVC pipe seats against (if you design your own it should have this shoulder as well)

Press the PVC pipe all the way up against that shoulder, then attach the front fitting, it does not have a step/shoulder, press it on until you see a clear magnified image, the distance between you and the object you are looking at may require you to re-position the front fitting..

If the image is upside down rotate the telescope 180 degrees. Just kidding this is how primitive telescopes work, the image is reversed!