So you have a Surface and you want to create some Thickness.

This script, allows you to select a surface (either with Trim Edges or without) and create an offset with Loft.

$selectedSur = `ls -sl`;
$offsetSur = `offsetSurface -ch on -m 0 -d 1 $selectedSur` ;
string $surEdges[] = `ls ($selectedSur[0] +".edge[*]")`;
string $offsurEdges[] = `ls ($offsetSur[0] +".edge[*]")`;
int $i = 0;
for ($i = 0;$i loft -ch 1 -u 1 -c 0 -ar 1 -d 3 -ss 1 -rn 0 -po 0 -rsn true $surEdges[$i] $offsurEdges[$i];
}

if (0 == size($surEdges)){
$minU = `getAttr($selectedSur[0]+".minValueU")`;
$maxU = `getAttr($selectedSur[0]+".maxValueU")`;

$minV = `getAttr($selectedSur[0]+".minValueV")`;
$maxV = `getAttr($selectedSur[0]+".maxValueV")`;
//check Seam
if (getAttr(($selectedSur[0]+".formU")) != 2){
loft -ch 1 -u 1 -c 0 -ar 1 -d 3 -ss 1 -rn 0 -po 0 -rsn true ($offsetSur[0]+ ".u[" + $minU +"]") ($selectedSur[0]+".u[" + $minU +"]");
loft -ch 1 -u 1 -c 0 -ar 1 -d 3 -ss 1 -rn 0 -po 0 -rsn true ($offsetSur[0]+ ".u[" + $maxU +"]") ($selectedSur[0]+".u[" + $maxU +"]");
}

if (getAttr(($selectedSur[0]+".formV")) != 2){
loft -ch 1 -u 1 -c 0 -ar 1 -d 3 -ss 1 -rn 0 -po 0 -rsn true ($offsetSur[0]+ ".v[" + $minV +"]") ($selectedSur[0]+".v[" + $minV +"]");
loft -ch 1 -u 1 -c 0 -ar 1 -d 3 -ss 1 -rn 0 -po 0 -rsn true ($offsetSur[0]+ ".v[" + $maxV +"]") ($selectedSur[0]+".v[" + $maxV +"]");
}

}