Попробуйте такой вариант:
Выделяем сплайн. Запускаем скрипт и нажимаем кнопку Apply.
Выделяем копию сплайна и добавляем модификатор Extrude.
Код:
try (destroyDialog igorznag_spline_dir) catch()
rollout igorznag_spline_dir "Spline Dir"
( button btn_apply "Apply"
checkbox cb_delete_old "Delete Old Splines"
on btn_apply pressed do
( undo on ( objs=#();for obj in selection do
if(classof obj==Line or classof obj==SplineShape)then
if(numKnots obj>=3)then append objs obj
objs_new=#(); for obj in objs do
( c=[0,0,0];p1=c;p2=c;t=1;
for i=1 to numSplines obj do for j=1 to numKnots obj i do
( p=getKnotPoint obj i j;c+=p
if(t==1)then p1=p;if(t==2)then p2=p; t+=1
)--for i,j
c/=numKnots obj; perp=cross (p1-c) (p2-c)
new_spline = splineShape();new_spline.pos=c;new_spline.dir=perp
for i=1 to numSplines obj do
( addNewSpline new_spline
for j=1 to numKnots obj i do
( kt=getKnotType obj i j; kp=getKnotPoint obj i j
kiv=getInVec obj i j; kov=getOutVec obj i j;
st=#line; if(j<numKnots obj i)then st=getSegmentType obj i j
else if isClosed obj i then st=getSegmentType obj i j
addKnot new_spline i kt st kp kiv kov
)--for j=1 to numKnots obj i do
if isClosed obj i then close new_spline i
)--for i=1 to numSplines obj do
updateShape new_spline; append objs_new new_spline;
)--for obj in objs do
if(objs_new.count==objs.count and cb_delete_old.checked)then
(select objs_new; delete objs)
)--undo on
)--on btn_apply pressed do
); createDialog igorznag_spline_dir