THERE'S A CERTAIN MYSTERY TO THE WAY IN WHICH ARTISTS CREATE THEIR WORK. THE FINAL PRODUCT ON VIEW IN A MUSEUM OR GALLERY COMES WITH LITTLE EXPLANATION ABOUT THE HOW AND WHY OF A PIECE. BUT NOW, AT THE WALKER ART CENTER, THREE SCULPTORS ARE LETTING THE PUBLIC IN ON THEIR CREATIVE PROCESS. THEY'RE WORKING IN ONE OF THE WALKER GALLERIES...AND THE PUBLIC IS INVITED TO STOP IN, WATCH AND ASK QUESTIONS. MARY STUCKY VISITED WITH ROBERT FISCHER THE FIRST OF THE THREE SCULPTORS IN WHAT THE WALKER IS CALLING "SCULPTURE ON SITE".