Milking and hand stretching
Pulling and squeezing require no materials, assembly, storage or money. Also called 'jelq,' with claims that the Sudanese Arabs have taught their boys these techniques for hundreds of years. Certainly, there are some big penises out there - so who knows? Described in various places with varying amount of confusion. Here I give you a basic introduction to you started.
Worn in private for 10-20 minutes at a time with breaks. Weigh from 2-10 pounds (1-4 kg). Biggest challenge is keeping weights attached to your penis. The best technique I know of is the swim cap - hang the most weight for the longest time...but can you get it to work for you? You can also use foam pipe insulation and a clamp, or the surgical tubing loop that appears in most commercial devices (but is too dangerous for me to recommend). Beyond that, there's the possibility of wrapping your penis with self-adhesive sports tape or a holy cloth, the way the Saddhus of India do.
The inventor of the 'Circle Device' claims endless potential; I haven't heard anything too convincing about this technique. Here's how to make your own 'circle device', bean bag and other weights that can be worn for hours at a time.
Many commercial devices are simply a loop attached to a rack which applies constant tension to the penis. You can build your own, but there are simpler and less conspicuous ways to apply constant tension. The expensive Penis Plus pulls your penis with a belt around your waist; this clever idea can be done with a simple Ace bandage. You can tie your penis to your leg.
Fabulous claims are made by the people who sell pumps, and indeed the first time you pump you'll be in awe of the mass of sausage hanging between your legs. Gradually, you'll realize your penis has become about as functional as a piece of sausage; the excess of lymphatic fluid squeezes your urethra shut, and instead of a stream of urine you can only produce an aerosol spray that goes everywhere. then you may notice you can't really get a firm erection, sometimes for several days; you may notice red spots on your penis head from burst capillaries, or painful lymph blisters on the head of your penis. And - inevitably - you'll wake up the next morning disappointed that all the gains have disappeared overnight. That said, pumping is pleasurable and a lot of people do it, so I give instructions for building your own pump and a fabulous orgasm device. Enjoy, but look elsewhere for permanent results.
Our society lives for magic bullets, and always seems surprised when they have unintended consequences. Surgery is dangerous, risky, and expensive. Don't even think about it!