Copy and paste the text below into WordPad, save the file as a text file, rename the file wo.ms, put the file in your scripts folder.

global baseVertex = 0
global baseTVertex = 0
global baseNVertex = 0

function toDec f = (
local i = f as integer
return i
)

function outputHeader =(
format "n"
format "Copy and paste the following lines into an"
format "text editor, and save them as a .obj file.n"
format "n"
format "# -----------------n"
format "# Start of obj filen"
flushStringStream
)

function outputFooter =(
format "# end of obj filen"
format "# ---------------n"
format "n"
flushStringStream
)

function outputNode node = (
format "g %n" node.name

local m = snapshotAsMesh node
for v = 1 to m.numVerts do (
local vert = m.verts[v]
format "v % % %n" vert.pos.x vert.pos.y vert.pos.z
flushStringStream
)
format "n"

if m.numtverts > 0 do (
-- Texture coordinates

for vt = 1 to m.numtverts do (
local tvert = getTVert m vt
format "vt % % %n" tvert.x tvert.y tvert.z
)
format "n"

-- Also print out the normals, because some importers
-- can't handle faces with textures but not normals

for f =1 to m.numFaces do (
local vn = getFaceNormal m f
format "vn % % %n" vn.x vn.y vn.z
flushStringStream
)
format "n"
)

local mv = m.verts
for f =1 to m.numFaces do (
local vface =getface m f
local x = baseVertex + toDec(vface.x)
local y = baseVertex + toDec(vface.y)
local z = baseVertex + toDec(vface.z)

if m.numtverts > 0 then
(
local tvface = gettvface m f
local tx = baseTVertex + toDec(tvface.x)
local ty = baseTVertex + toDec(tvface.y)
local tz = baseTVertex + toDec(tvface.z)
local n = baseNVertex + f
format "f %/%/% %/%/% %/%/%n" x tx n y ty n z tz n
flushStringStream
)
else (
format "f % % %n" x y z
)
)
format "n"
baseVertex = baseVertex + m.numVerts
baseTVertex = baseTVertex + m.numtverts
baseNVertex = baseNVertex + m.numFaces
)

function PrintObj = (
outputHeader()
for c in rootNode.children do outputNode c
outputFooter()
)

PrintObj()