Thanks for your answer, Mark Unfortunately, i can't use the solution you suggested, because my computer is way too slow ! For info, i use a little Celeron 400 with only 64 kB ram ( oops, i mean 64 "mB" . 64 kB was on my Amstrad CPC ! ) . Look the message Carrara gives me ( who say there's nothing new about that prog ??? ) when i use a too complex spiral : it's not a crash, but the process takes minutes . And i have already used this technique for the horns . The program calculates the deformed spline object each time i open the file . It's slow enough for me ! But thanks anyway, i didn't think of it . litst