Reversing the Lens with a Reversing Ring
Use a "reversing ring" to reverse the lens on the camera for about $20. This special attachment connects to the filter thread on the front of a lens and connects the front of the lens to the camera body. The lens is now in reverse. Excellent high quality results can be obtained using this cheap attachment. Use Nikon cameras with reversing rings. I have a 12 year old Nikon 50mm lens with which I can manually change the aperture while it is off the camera (and on a reversing ring), and it works with modern Nikon cameras! I get about 1x magnification without any extension rings with a working distance of 4 inches away from the subject.
A reversing ring adapter is available for Canon EOS allowing for electronic connection for several hundred dollars. For the same price you could get a whole macro lens! A reversing ring or adapter is available for old Canon mount models for about $20. As with lens to lens stacking, a rear filter cap with a round opening cut into it is advisable to protect the rear element of the reversed lens. Remember, the aperture on some lenses is not able to stay open on their own while it is off the camera so check your lens first before buying a reversing ring (aka reversing adapter).
A salesman recently asked me “Why do you want to buy a reversing ring? We have macro lenses. Reversing rings are an old fashioned way to do things!” I guess it is also old fashioned to save several hundred dollars. Why not spend $20 for a reversing adapter instead of $800 on a nice macro lens? You can get high quality results with a reversing ring and get some experience with macro photography! You can always spend the several hundred dollars later on a nice macro lens that will be easier to use, and give you more options.