This script copys vertex groups and weights from 1 weighted mesh, to all unweighted meshes.

It just uses the closest to copy the weights, but this means the meshes need not have the same number of verts.
Worldspace coords are used so the meshes only need to overlap in worldspace.

release/scripts/mesh_boneweight_copy.py

@@ -0,0 +1,94 @@
+#!BPY
+"""
+Name: 'Bone Weight Copy'
+Blender: 241
+Group: 'Object'
+Tooltip: 'Copy Bone Weights from 1 weighted mesh, to other unweighted meshes.'
+"""
+import Blender
+from Blender import Armature, Object, Mathutils, Window, Mesh
+Vector= Mathutils.Vector
+
+def copy_bone_influences(_from, _to):
+	ob_from, me_from, world_verts_from, from_groups=  _from
+	ob_to, me_to, world_verts_to, dummy=  _to	
+	del dummy
+	
+	def getSnapIdx(vec, vecs):
+		'''
+		Returns the closest vec to snap_points
+		'''
+		close_dist= 1<<30
+		close_idx= None
+		
+		x,y,z= tuple(vec)
+		for i, v in enumerate(vecs):
+			# quick length cmp before a full length comparison.
+			if\
+			abs(x-v[0]) < close_dist and\
+			abs(y-v[1]) < close_dist and\
+			abs(z-v[2]) < close_dist:
+				l= (v-vec).length
+				if l<close_dist:
+					close_dist= l
+					close_idx= i
+		return close_idx
+	
+	from_groups= me_from.getVertGroupNames()
+	for group in from_groups:
+		me_to.addVertGroup(group)
+	
+	add_ = Mesh.AssignModes.ADD
+	
+	for i, co in enumerate(world_verts_to):
+		
+		from_idx= getSnapIdx(co, world_verts_from)
+		from_infs= me_from.getVertexInfluences(from_idx)
+		
+		for group, weight in from_infs:
+			me_to.assignVertsToGroup(group, [from_idx], weight, add_)
+	
+	me_to.update()
+	
+
+def worldspace_verts(me, ob):
+	mat= ob.matrixWorld
+	def worldvert(v):
+		vec= Vector(v)
+		vec.resize4D()
+		vec= vec*mat
+		vec.resize3D()
+		return vec
+	
+	return [ worldvert(v.co) for v in me.verts ]
+
+def main():
+	sel=[]
+	from_data= None
+	for ob in Object.GetSelected():
+		if ob.getType()=='Mesh':
+			me= ob.getData(mesh=1)
+			groups= me.getVertGroupNames()
+			
+			data= (ob, me, worldspace_verts(me, ob), groups)
+			if groups:
+				if from_data:
+					Blender.Draw.PupMenu('More then 1 mesh has vertex weights, only select 1 mesh with weights. aborting.')
+					return
+				else:
+					from_data= data
+			else:
+				sel.append(data)
+	
+	if not sel or from_data==None:
+		Blender.Draw.PupMenu('Select 2 or more mesh objects, aborting.')
+		return
+	
+	Window.WaitCursor(1)
+	# Now do the copy.
+	for data in sel:
+		copy_bone_influences(from_data, data)
+	Window.WaitCursor(0)
+
+if __name__ == '__main__':
+	main()