I make my own dildos and butt plugs using silicone.
You have to use 100% pure silicone which is food safe, this should be available from most hardware stores as its also used in fish tanks.
Once you have the silicone don't bother trying to mould it with a mould as the mould seals the silicone from the air and it will take months to set.
This had me stumped for years as it always took too long to set so I used many other materials instead such as EVA closed cell foam, latex over all sorts of things, vegetables etc.
Eventually I figured out the secret to making your own dildos, and here it is:
You need to catalyse the silicone, this means starting the chemical reaction to make the silicone harden.
This catalyzation process is normally set off by the air but you can accelerate it and have a dildo in less than 1/2 an hour!
This is what you will need:
1) 100% Silicone
3) dish-soap any brand should work
4) large bowl
5) caulking gun
Make a catalyzing bath.
I use about 120g/4oz of soap in 2L of water.
The Glycerine in the soap acts as a catalyzer and accelerates it setting.
Then unload the required amount of silicone from the tube using your caulking gun directly into the water, the water will prevent it sticking to the bowl and your hands.
This is good as the next step is to knead it with your hands to get as much of the silicone in contact with the soapy water.
After 5 mins or so of kneading you will notice the silicone become less knead-able, at this point you need to start moulding your desired dildo/buttplug shape.
The soapy water acts as a lubricant so its very easy to mould into a smooth shape which can be easily introduced to the desired area.
I would recommend making a base that not only allows you to get a good grip when its lubed up but also once it has set enough you can stand it on the base while it fully sets.
While the silicone sets in under half an hour I generally leave it for a day or two to fully catalyze as when first set it has a very strong smell.
Give it a good wash, lube up then enjoy.