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I wish to create a basic rectangle with a hole in it to the scene upon running the python script. I understand how to create a simple cuboid - however I can't find an easy way of creating one with a rectangular hole through the centre short of splitting it up into four rectangles however I want it to be one structure.

My code for the cuboid so far is:

import bpy

verts = [(0,0,0),(0,5,0),(1,5,0),(1,0,0),(0,0,5),(0,5,5),(1,5,5),(1,0,5)]
faces = [(0,1,2,3), (4,5,6,7), (0,4,5,1), (1,5,6,2), (2,6,7,3), (3,7,4,0)]

grat1mesh = bpy.data.meshes.new("grat1")
grat1obj = bpy.data.objects.new("grat1", grat1mesh)
grat1obj.location = bpy.context.scene.cursor_location
bpy.context.scene.objects.link(grat1obj)
grat1mesh.from_pydata(verts,[],faces)
grat1mesh.update(calc_edges=True)

Any help is appreciated, thanks.

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Using from_pydata

Make an inner and outer square of vertices for top and bottom. Fill top with 4 trapezium faces. All other face indexes can be calculated from the top faces by adding appropriate index offset to them.

enter image description here

import bpy
from mathutils import Vector
context = bpy.context

scene = context.scene
mesh = bpy.data.meshes.new("mesh")
# 2d square
def xysquare2d(z=0, scale=1):
    r = [-scale, scale]
    return [Vector((x, y, z)) for x in r for y in r]

verts = []
# top verts
verts.extend(xysquare2d(z=2, scale=2))
verts.extend(xysquare2d(z=2))
# bottom verts       
verts.extend(xysquare2d(z=-2))
verts.extend(xysquare2d(z=-2, scale=2))
top_faces = [(0, 1, 5, 4), 
         (1, 3, 7, 5),
         (3, 2, 6, 7),
         (2, 0, 4, 6)]
# make all the other faces from top faces
bottom_faces = [(i + 8, j + 8, k + 8, l + 8) for i, j, k, l in top_faces]
outer_faces =  [(i, j, k + 8, l + 8) for i, j, k, l in top_faces]
inner_faces =  [(i + 8, j + 8, k, l) for i, j, k, l in top_faces]
# add them 
faces = top_faces  + bottom_faces + outer_faces + inner_faces

mesh.from_pydata(verts, [], faces)
obj = bpy.data.objects.new("obj", mesh)
scene.objects.link(obj)

Can create pydata from a mesh.
Make the model, then run this script on the mesh.

print("verts = [")
for v in mesh.vertices:
    print("\t", [axis for axis in v.co], ",")
print("\t]")
print("faces = [")
for f in mesh.polygons:
    print("\t", [i for i in f.vertices], ",")    
print("\t]")

Which when run on mesh created above results in

verts = [
     [-2.0, -2.0, 2.0] ,
     [-2.0, 2.0, 2.0] ,
     [2.0, -2.0, 2.0] ,
     ....
     [2.0, 2.0, -2.0] ,
    ]
faces = [
     [0, 1, 5, 4] ,
     [1, 3, 7, 5] ,
     ....
     [10, 8, 4, 6] ,
    ]

Using boolean modifier

If you don't mind ngons, can use boolean difference, append this script to your original

# copy the mesh
grat2obj = grat1obj.copy()
grat2obj.data = grat1mesh.copy()
scene.objects.link(grat2obj)
# move it up 1, 1
grat2obj.location += Vector((-0.5, 1.25, 1.25))
# scale it 
grat2obj.scale = (2, 0.5, 0.5)

# add a boolean modifier
bm = grat1obj.modifiers.new("Chop", 'BOOLEAN')
bm.object = grat2obj
bm.operation = 'DIFFERENCE'
# apply the modifier
scene.objects.active = grat1obj
bpy.ops.object.modifier_apply(modifier=bm.name)
# remove chopper
scene.objects.unlink(grat2obj)

Using bmesh

Add a plane, inset it, remove middle face, solidify.

import bpy
import bmesh
mesh = bpy.context.object.data
bm = bmesh.new()
bmesh.ops.create_grid(bm,
                      x_segments=2,
                      y_segments=2,
                      size=1)

bmesh.ops.inset_individual(bm, faces=bm.faces, thickness=0.3)
# take out middle
[bm.faces.remove(f) for f in bm.faces if all(not e.is_boundary for e in f.edges)]                  
# extrude
bmesh.ops.solidify(bm, geom=bm.faces, thickness=1) 
bm.to_mesh(mesh)
mesh.update()
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  • $\begingroup$ Thanks a bunch that was the best explanation I could've wanted. Thought it might've been slightly easier than this, however! $\endgroup$ – CooperCape Sep 27 '17 at 18:54
  • $\begingroup$ it's late, I'll get around to bmesh later. With bmesh you don't have to keep tabs of the vert indices. Possibly easiest to add two prim cubes, remove tops, then bridge. Or 4 traps and extrude. Is there any particular reason you want to use from_pydata. $\endgroup$ – batFINGER Sep 27 '17 at 19:01
  • $\begingroup$ Not at all. I'm sure I can work around it if there's an easier solution. Just seemed easier at the time to plot out a basic cube that way - and as such I thought a basic cube with a hole would be similar. $\endgroup$ – CooperCape Sep 27 '17 at 19:05

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