A user afternine asked for some info on making his own silicone toys, and I didn't want to take the thread off topic, so here it is.
Disclaimer
I don't accept responsibility for the accuracy or availability of this information or the links in this post. I dont get a dime from these vendors, just trying to give people a jump start on what took me months of research to catch up on. If you make a butt plug with soft, low tear strength silicone with a neck that is too thin and it breaks off in your butt, that is your fault, not mine. Its important that you think for yourself and make sure you understand before you act.
Forward
I started making silicone toys after growing tired of paying $100 or more for toys made of questionable materials or double or triple that much for silicone toys.
Learning
You first need to understand silicone and the Shore durometer scale to understand what you are going to end up with and to be sure it will be safe and comfortable to use.
Wikipedia:
http://en.wikipedia.org/wiki/Shore_durometer
http://en.wikipedia.org/wiki/Silicone
http://en.wikipedia.org/wiki/Silicone_rubber
Suppliers
The US supplier I have worked with is a company called Smooth-On (http://www.smooth-on.com/Silicone-Rubber-an/c2/index.html). Smooth-On also operates a company called Reynolds Advanced Materials (http://www.reynoldsam.com/)
They offer a full line of silicones, both platinum (addition cure) and tin (condensation cure) based. They also have a lot of other awesome stuff, like pigments, release agents, solvents, and other plastics, rubbers, epoxies, and thermoplastics.
Products that you might need:
Mold Star® 15, 16 and 30 Silicones
http://www.smooth-on.com/Silicone-Rubber-an/c2_1115_1341/index.html
Low viscosity, great for making molds, but has a low tear strength so I stay away from it for the finished products.
Smooth-Sil® Platinum Cure Silicone Rubber
http://www.smooth-on.com/Silicone-Rubber-an/c2_1115_1131/index.html
This is what I've used most often, in the 35-45A durometer. Makes great toys, not overly flexible, but still tons of fun.
Dragon Skin® High Performance Silicone Rubber
http://www.smooth-on.com/Silicone-Rubber-an/c2_1115_1129/index.html
This is what you would use for something more flexible
Silc Pig® Silicone Pigments
http://www.smooth-on.com/Silicone-Rubber-an/c2_1128_1190/index.html
Get the color you want. Buy the variety kit or the colors you want.
Release Agents & Sealers
http://www.smooth-on.com/Release-Agents-and/c9/index.html
The release agent, solvents, and sealers you might need depending on your application.
Ease Release® 200 and 205
http://www.smooth-on.com/Release-Agents-and/c9_1123_1226/index.html
This is far better than cooking spray to make sure you don't end up with everything stuck together.
There are tons of other products on there, use your head, think about what you are trying to make and what is safe. Avoid anything that could break off and get lost.
There are other suppliers in the US (example Freeman Manufacturing http://www.freemansupply.com/), and certainly suppliers in Europe and elsewhere.
Videos
Watch tons of videos
Smooth-On has lots: http://www.smooth-on.com/media.php
Freeman has lots too: http://www.freemansupply.com/video.htm
YouTube accounts that have a ton of good videos:
http://www.youtube.com/user/brickintheyard
http://www.youtube.com/user/SmoothOnInc
http://www.youtube.com/user/freemanmfg
Examples of the right way to do it:
http://www.youtube.com/watch?v=48UwkzNqREA
http://www.youtube.com/watch?v=FQ1A7ZjTsx8
An example of a crappy but functional approach:
http://www.youtube.com/watch?v=kRpdOkwitFE
Tools & Equipment
Unfortunately, tooling is expensive. You need a vacuum chamber & pump to get the tiny air bubbles out of the silicone after its mixed or you end up with little bubbles all over your end product. You can get vacuum pump and chamber setups from lots of places, but make sure you get one that is big enough. At the moment it degases, it will expand ~3x its resting volume all sudden like. This means 2 gallons of mixed silicone might overflow a 6 gallon bucket. I got mine from eBay, its a 10 gallon setup that easily holds a 6 gallon bucket of silicone. I went into this planning on starting a business, but I haven't gone down that road yet. Plan on $300-400 for the whole setup.
You also need mixing and measuring buckets (these should have volume markings on the side of them, 1, 2, or 3 liter sizes are good), stiring implements, a good digital scale that measures in grams up to 10 or 20 kilos. A nice big box of nitrile gloves is nice to have as well, for so many reasons.
On the mold making side, you need something to make mold boxes out of, I use plexiglass, but you could use anything you wanted. I put it together with silicone caulk or hot glue. For alignment I use acorn nuts, they are big and robust and you get good mold alignment. Add a few simple strap clamps, a nice big box of disposable scalpels, and a bunch of modeling clay and you are probably good to give it a try.
I'm not going to go into detail on the how, just watch the videos and let your imagination do the work.
It is a lot of work, but you get exactly what you want at a lower price in the long run. I've made a whole selection of dilators, as well as a few tunnel plugs, a copy of a 1.75" wide, 18" long Doc Johnson double dong, and modified that to make a 24" one. At this point, I have started saving money, but figure that is somewhere around 15 pieces. Its mostly about defraying the cost of the vacuum rig. I like that I still have the molds if something happens to one of them or I want another one later.
Notes
-Make sure you note whether you are supposed to measure your silicone by volume or weight, it is critical that the ratio is true and correct.
-The silicone will precisely copy whatever is on the model, right down to the finish texture.
-If you use clay to make the model, make sure you bake it or let it dry hard and then spray it with a clear coat if you want a smooth finish. For clay, also make sure you use a sealer (smooth on has this as well)
-Release agent is your friend. Put it on everything you don't want silicone stuck to forever.
-Make sure you mix your silicone thoroughly.
-I can't stress enough that you are taking your personal safety in your own hands when you make your own toys. Use your head (I mean the big one, not the little one), and think everything through before you get a big lump of silicone lodged in your descending colon.
Other applications
Recently I've started work making a mold for glycerine suppositories. I want something between the size they come in and the massive size of a condom. You can also make soap molds, candy molds, cookie pans, ice cube molds, and about a thousand other things if you want.