Begin your design by laying two of the calla stems against each other, keeping the heads fairly level - maybe just a little staggered.
Tape together several inches down the stem, forming a pronounced "V" space between the calla stems.
Tape securely, pulling the tape so that it stretches and adheres to itself.
Place a third calla stem in the "V" space between the first two callas, pressing firmly against the back of those flowers.
Tape the third calla into place with florist tape as with the first two stems.
Choose a fourth stem of calla to use in the design.
Place this along side the other stems, staggering the head so that it is not exactly the same height as the other flower heads.
Tape the fourth calla stem securely into place with florist tape.
Add more callas until you are satisfied with the look, staggering the heads as you tape the stems together.