1. Biometar MC 80mm f/2,8 lens(I got mine for $60).
2. M42 macro rings($10).
3. M42/nikon/canon converter($10).
4. A 2.25 inches long piece of bicycle inner tube.
5. Hose clamp.
6. 20 minutes.
This is really easy and quick project to make.
Once you get all the parts it almost takes no time to make this lens.
I had a lot of fun building and using that lens.
Step 1: Put a Tube Onto the Lens.
This is a bit tricky step.
Make sure you are not using a tube from street bike. It's best to find rather wide inner tube.
I had an old piece of inner tube from a mountain bike and it fits really well.
Step 2: Macro Ring.
Macro ring goes on the other side of the tube.
Make sure to put the tube a bit over the edge of the ring so it's easy to clamp it with m42 converter.
Step 3: M42 Converter.
This one goes on a macro ring. Make sure it clamps the tube. You don't want this coming of while shooting pictures.
Step 4: Make a Tiny Hole in the Tube for the Aperture Pin.
This will allow the aperture to open and close. You could skip this process but then you'll be stuck with aperture fully opened.
Step 5: Add a Hose Clamp to Secure the Tube on the Lens.
This will ensure your lens stays in one piece at all times.
Step 6: Results...
This is a really fun toy.
Note, that is not something you would use for building photography etc.
This is definitely a great lens for having fun with focus depth and plane.