You can alter the shape of your gourds by various means while they are growing. I am not an expert but I am glad to share what I know from personal experience. Try one of these methods and see how it works for you.

FLAT GOURDS
This can be done with forms made of Plexiglas, plate glass or wood. Cut two pieces in the desired size and drill holes in all four comers. Decide on the depth that you want the gourd to be and cut four posts from dowel rods or broom handles. Drill holes through the center of the posts going from one end to the other. Purchase bolts, wing nuts and washers of the appropriate size and length. Assemble the form and it is ready to use. Note: The mold must be neither too large or too small for the gourd that you intend to work with. Place a young gourd inside the mold with the center of the gourd in the center of the form or mold. In just a few days the gourd will be firmly pressed against the mold. The power of a growing gourd is amazing. Gourds will break 3/16" Plexiglas or plate glass. So you see why the size of the mold is so important: too small and the gourd will break the mold. Leave the gourd inside the mold until time to harvest.

SQUARE GOURD
This is a gourd that is flat on four sides when it is finished growing. Make open ended molds of Plexiglas and fasten together with bolts and wing nuts. Use the same growing method as described above. I have used miniature Japanese Bottle Gourds for this method of shaping and was very pleased with the results.

GROWING GOURDS IN JARS
Grow a gourd in a jar by simply placing it in the jar and prevent water from entering. Water will cause the gourd to decay. I used crumpled plastic wrap around the opening of the jar. After the gourd has filled the jar, it can be hoisted upwards with twine so the mouth of the jar is pointing down. When the gourd is mature the jar can be removed by wrapping it with cloth and gently tapping with a hammer. It is also a good idea to wear protective goggles when breaking the jar.

CORKSCREW HANDLES
These gourds should be grown on a trellis. To make a corkscrew handle, select a dipper or snake gourd that is about two weeks old and is growing from the top of the trellis. Prop a broom stick on the trellis at an approximate 30 degree angle and tie it to the top with twine. Very gently and carefully start twisting the young gourd around the stick. Don't try to do this all at once. To hold the gourd in the twisted shape use thick strips of nylon hose tied loosely, near the bottom of the gourd. It may be necessary to drive stakes in a circle on which to tie the nylon that holds the gourd in place. Continue twisting the gourd as it grows and until it becomes too firm to manipulate. It is possible to increase twists two times a day.

ROPE TRAINING
Simply wrap and tie ropes around the gourds that are about one half to two thirds maximum size. Be creative and see what unusual shapes you can come up with. Be sure to use a firm rope or twine as stretchy material will not give the proper support.

TYING A KNOT
The only gourd that can be used for this procedure is the long handled dipper. The longer the handle, the better. Start tying the knot the first or second day after bloom. The gourd is already formed on the female blossom at this time. Attempt the procedure during the hottest part of the day when the tiny gourd is more supple. Involve the gourd stem in tying a very loose overhand knot. Do not attempt to tighten it at this time. As it grows the weight of the gourd will tighten the knot. You may need to make adjustment along the way. Knot gourds should be grown on a fence or trellis. Tom Teruo Matsumoto has been successful in tying a double knot, also known as a husband and wife knot.