To experiment with the Ganzfeld effect, you need to create a suitable Ganzfeld (or several Ganzfelds if you aim for multi-modal Ganzfeld). One way to make a visual Ganzfeld is to use so-called "Ganzfeld goggles" and a bright light.
To build Ganzfeld goggles, you need: - ping-pong balls - some sandpaper - a sharp knife (for example a mat-cutting knife) - a pencil - about half an hour of time
The idea is to take this little thing:
...and turn it into two things which look something like this:
Before You Begin...
Some tools and material are needed, so make sure you have them before you start. In the picture below, from left to right, there are 1. the ping-pong balls (blue box), 2. a pencil, 3. some painter's tape (which was not used), 4. sandpaper, and 5. a sharp knife.
The sandpaper should be quite fine-grained. As seen from the next picture, I bought sandpaper with FEPA P-Grade of P150, which means the particle size is about 97 microns (yes, I am just as amazed as you are why I happen to know that). Note, you won't need much sandpaper, so if you usually don't need sandpaper at all, it will be cheaper to buy just a few small pieces of it, instead of a roll with many meters.
Before you begin, make sure to be careful when cutting the ping-pong balls - they can be difficult to cut and the plastic can give in at the most unexpected moment. As for altered states of consciousness, the ones we are now interested in are those induced by an MMGF, not by a near-death experience. So please be careful and try to avoid cutting yourself fatally with the knife.
Cut the Ping-Pong Balls in Two
First thing to do is to cut the ball in half. The seam is probably the best place to cut, although I did not do so when cutting the ball shown in the image. In any case, try to make as straight and even cut as you can.
Notice also how the edge is very, very rough and consequently somewhat sharp. You do not want to place anything so sharp near your eyes, so later any sharp and rough bits will be sandpapered away.
Make a Curvature for the Eye Socket
Next thing to do is accommodate for the curvature of the eye socket. For this you need to draw, with the pencil, a curve similar to the one shown in this picture:
Next, you need to cut the curve with the knife. It's best to try to make small cuts, as if carving an object out of wood. After trashing two ball-halves, I noticed that the cuts are good and small enough when you're getting small, curly scrap (as displayed in the following picture).
After you've cut the curvature, sandpaper out any rough edges. At this point you can also sandpaper out the logo from the balls, and any remnants of pencil markings.
What you have then should be a fully white egg-shell like hemisphere, which fits snugly into your eye socket without letting light in from the edges.
Try it Out
Now you're all set for a multi-modal Ganzfeld experiment. Find a nice spot to lie down. Set up a bright lamp so that it will shine on your face. When you have your eyes open, you should see just a white "nothingness". This is the Ganzfeld for overloading your visual inputs. Load your MP3 player with suitable white, brown or pink noise - this will be used to overload your aural inputs. Put on the earphones, put on your brand new goggles, and enjoy the experimenting!