To make an ejaculating sex toy:

Print the version of the mold designed for cum tubes. This mold will have a prong in the tip of the toy, like this

Cut the tube as long as you'd like it to be, then press the other end of the tube over a 10-gauge Luer-lock blunt needle. Fit the Luer lock into a Luer syringe.

Mix, color, vacuum, and pour the silicone. Note: If you're making the cum tube version, make sure the cum tube extends from the center of the opening in the mold. You can place pencils across the top of the mold to hold the tube in place while the silicone cures.

For best results, make sure the cum tube doesn't touch the outside edge of the mold. With some designs, such as the tentacle butt plugs, this is easy. With some, like the tentacle ball gag, it isn't. If the tube touches the outside edge of the mold, it will be visible on the surface of the finished toy.

For the ball gag, routing the silicone cum tube through the mold can be a little tricky. It's helpful to cut the tube the length you want it to be, then cut a piece of wire just a little longer. Thread the wire through the cum tube, then bend the wire to hold the tube away from the edge of the mold like so:

You can fill a mold partway with one type of silicone, let it cure, then fill it the rest of the way with a different grade of silicone. For example, to create a particularly authentic hentai experience with a tentacle ball gag, you can fill the mold with 21ml of soft, squishy 00-20 grade silicone, then let it cure and fill the rest of the way with Dragon Skin 20 silicone.

If you're designing your own sex toys in a 3D modeling program, make the stem about 0.1 to 0.2 mm larger than the inside diameter of the cum tube you plan to use. If you use 3mm inside diameter/5mm outside diameter tubing, make the stem 3.1-3.2 mm in diameter.

You want the stem long enough to let the tube slip at least 3mm or so onto the stem, but also long enough to keep the tube 3-5mm away from the end of the toy.

Want higher fluid flow rates? Use 5mm inside diameter/7mm outside diameter silicone tubing. This tubing is wide enough it can be press-fitted directly over the end of high-capacity catheter-tip plastic syringes.

 

What You’ll Need

• Use only food-grade silicone for the cum tubes. This is safe, non-toxic, and hypo-allergenic, and it's compatible with silicone. Some materials, including latex, inhibits silicone curing. If you use a cum tube containing latex or certain other materials, the silicone will not cure anywhere it touches the tube, and your sex toy will be ruined.