The U-shaped cousin of L-angle, three faces of an open box rather than two. The trim profile that runs along the edge of every plywood case lid, the structural channel that takes a heavy bookshelf load, the shoe-track that holds a sliding door. Comes in inches (1 × 1/2 × 1/16 wall is a common small-shop size) and metric. Slides over a panel edge to protect it (trim use), or fastens flat against a face to carry a load (structural use). The 6061-T6 grade for structural, 6063-T5 for visible architecture. Buy by the foot at the hardware store for trim work, by the 12-foot stick at McMaster-Carr or MSC for structural projects. The fixture / fabricator / scenic shop standby alongside L-angle.
Extruded aluminum U-section in 6061-T6 (structural) or 6063-T5 (architectural). Sizes from 1/2 × 1/4 × 1/16 (small trim) up to 8 × 4 × 1/2 (heavy structural channels approaching small-I-beam capability). The 1 × 1/2 × 1/16 inch reference size has cross-section ~0.094 in² (61 mm²), weight ~0.110 lb/ft (~0.16 kg/m). Larger 2 × 1 × 1/8 reference size has cross-section ~0.469 in² (303 mm²), weight ~0.55 lb/ft (~0.82 kg/m) — a useful structural channel for fabricator work. Section modulus and moment of inertia per AA DS-1 / AISC tables; the channel's open side reduces torsional stiffness vs. a closed tube but increases bending stiffness per unit weight in the open-side-down orientation. Tolerances per Aluminum Association DS-1; web and leg dimensions held to ±0.030 inch typical. Cuts on a non-ferrous chop saw; drills and taps cleanly. The web (the closed face) is the load-carrying surface for through-bolts; the legs (the open faces) are where panel edges seat for trim use. Anodizes for visible architecture; mill-finish for hidden fabrication.
Principled BSDF defaults derived from the sphere metallic finish. Reasonable seed for Blender, Substance, Keyshot, Rhino — tune per material. Or grab the whole library at once: ForMaterials library →
# finish: metallic albedo #b8b8bc metallic 1.00 roughness 0.50 ior 1.45 transmission 0.00 clearcoat 0.00 sheen 0.00 anisotropic 0.00
{
"albedo": "#b8b8bc",
"metallic": 1.0,
"roughness": 0.5,
"ior": 1.45,
"transmission": 0.0,
"clearcoat": 0.0,
"sheen": 0.0,
"anisotropic": 0.0
}
# Blender 4.x — Principled BSDF
# Aluminum Extruded U-Channel (Structural) · finish: metallic
import bpy
mat = bpy.data.materials.new(name="mat_aluminum_extrusion_channel_u")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value = (0.4793, 0.4793, 0.5029, 1.0)
bsdf.inputs["Metallic"].default_value = 1.000
bsdf.inputs["Roughness"].default_value = 0.500
bsdf.inputs["IOR"].default_value = 1.450
bsdf.inputs["Transmission Weight"].default_value = 0.000
bsdf.inputs["Coat Weight"].default_value = 0.000
bsdf.inputs["Sheen Weight"].default_value = 0.000
bsdf.inputs["Anisotropic"].default_value = 0.000
# KeyShot 11+ — lux Python API, Generic material
# Aluminum Extruded U-Channel (Structural) · finish: metallic
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_aluminum_extrusion_channel_u", materialType="Generic")
mat.setProperty("diffuse", (184, 184, 188)) # 8-bit sRGB
mat.setProperty("metallic", 1.000)
mat.setProperty("roughness", 0.500)
mat.setProperty("indexOfRefraction", 1.450)
mat.setProperty("transparency", 0.000)
mat.setProperty("coatingWeight", 0.000)
{
"_format": "Substance Designer / Painter \u2014 pbrMetalRough constants",
"_about": "Aluminum Extruded U-Channel (Structural) \u00b7 finish: metallic",
"baseColor": {
"r": 0.4793,
"g": 0.4793,
"b": 0.5029
},
"metallic": 1.0,
"roughness": 0.5,
"ior": 1.45,
"opacity": 1.0,
"anisotropyLevel": 0.0,
"_notes": "Channels listed are the standard Substance pbrMetalRough output. Drop into a Uniform Color node per channel, or as the constant input on a layered stack."
}{
"asset": {
"version": "2.0",
"generator": "ForMatter"
},
"materials": [
{
"name": "mat_aluminum_extrusion_channel_u",
"pbrMetallicRoughness": {
"baseColorFactor": [
0.4793,
0.4793,
0.5029,
1.0
],
"metallicFactor": 1.0,
"roughnessFactor": 0.5
},
"extensions": {
"KHR_materials_ior": {
"ior": 1.45
}
}
}
]
}# USD Preview Surface — UsdShade.MaterialLook prim attributes
# Aluminum Extruded U-Channel (Structural) · finish: metallic
def Material "mat_aluminum_extrusion_channel_u" {
token outputs:surface.connect = </mat_aluminum_extrusion_channel_u/PreviewSurface.outputs:surface>
def Shader "PreviewSurface" {
uniform token info:id = "UsdPreviewSurface"
color3f inputs:diffuseColor = (0.4793, 0.4793, 0.5029)
float inputs:metallic = 1.000
float inputs:roughness = 0.500
float inputs:ior = 1.450
float inputs:opacity = 1.000
float inputs:clearcoat = 0.000
token outputs:surface
}
}
Aluminum Association; ASTM B221.
House vocabulary — terms ForMatter uses with intent.
Materials and processes for people who design and make things.
A local-first library of materials, processes, applications, and finishes — equal weight, citable everywhere, so a student can move from "what is this" toward "what's actually buildable here, now, by me." Part of the renato.design ecosystem — sibling of Plenum, Specimen, Ingenue, gesture, graf, and the Renato Rhino plug-ins. Form and matter, inseparable.
Half of teaching materials is teaching how the material is made into the thing. The standard subscription library was always light on that half. The wedge here isn't better samples or a prettier interface — it's treating Process as a peer entity, not a footnote.
Conway, Lefteri, Forty, Sparke, ASM, GIA. Every voice: Voices.
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