RandomPrimParams

integer int=3;

default {

state_entry() {
llSetTimerEvent(0.1); // How fast repeat event
}
timer() {
   float r = llFrand(1);
   float g = llFrand(1);
   float b = llFrand(1);
   float r2 = llFrand(1);
   float g2 = llFrand(1);
   float b2 = llFrand(1);
if(int==1) 
++int; 

llSetLinkPrimitiveParamsFast(LINK_SET, [PRIM_COLOR,ALL_SIDES, <r,g,b>, 1.0]); // You can use every PrimParams here like for example PRIM_GLOW

} else { 
int=1;

llSetLinkPrimitiveParamsFast(LINK_SET, [PRIM_COLOR,ALL_SIDES, <r2,g2,b2>,1.0]); // Same here

} 
}

}