The short answer
On housing RFQs, a **cosmetic A-side** is not the same note as a **B-side**, and neither is covered by “make it look good” in a title block. A-side is the primary visible or customer-facing surface: tighter finish, fewer witness marks, and often the face that must match after anodize or chem film. B-side is the secondary face where clamp marks, a rougher mill pattern, or a residual tab may be allowed if you say so. Silence on which faces are A-side, on whether vise marks may remain on B, and on how finish is measured after coating, is what widens many [quote-new.php](https://3dwk.com/quote-new.php) **rates.v1.1** estimate bands—not the milling minutes alone.
This guide is for buyers packaging aluminum housing RFQs where CAD shows every face as a class-A cosmetic wall, or a notes cloud that says “no tool marks.” Illustrations use an **Example part** only—not a customer electronics enclosure. Sibling notes live in [edge-break and deburr callouts](https://3dwk.com/resources/edge-break-chamfer-deburr-callouts-cnc) and [five-axis aluminum housing design tips](https://3dwk.com/resources/five-axis-aluminum-housing-design-tips); here we focus on **A-side versus B-side packaging** so estimators do not treat every wall as show-room.
What A-side and B-side mean for quoting
**A-side** is the face (or face set) a buyer will see, photograph, or present: a lid exterior, a front bezel, or a named cosmetic wall. **B-side** is the opposite or interior face where a clamp, a soft jaw, or a rougher pass is acceptable if labeled. The split is a packaging choice, not a hidden ISO class. Process pages for electronics-thermal aluminum ([CNC 5-axis Al 6061 electronics-thermal](https://3dwk.com/en/cnc-5axis/al-6061/electronics-thermal.html), [CNC 5-axis Al 6061](https://3dwk.com/en/cnc-5axis/al-6061.html), [CNC 3-axis Al 6061 electronics-thermal](https://3dwk.com/en/cnc-3axis/al-6061/electronics-thermal.html)) assume face-class notes when lots mix cosmetic lids with utility interiors.
Do not bury “no marks anywhere” inside a notes cloud. Put **FACE A COSMETIC A-SIDE, Ra 1.6, NO VISE WITNESS; FACE B B-SIDE, CLAMP WITNESS OK OUTSIDE DATUM D; EDGES 0.2–0.4 BREAK** on the PDF and mirror it in RFQ text. Background: [DFM checklist before an online CNC quote](https://3dwk.com/resources/dfm-checklist-before-online-cnc-quote), [what files to send for a CNC quote](https://3dwk.com/resources/what-files-to-send-for-cnc-quote).
Finish, coating, and matching faces
A-side often carries the tighter [Ra callout](https://3dwk.com/resources/surface-roughness-ra-for-machined-parts) and the coating that must look even. If Type II anodize or [chem film](https://3dwk.com/resources/when-to-specify-chem-film-after-cnc-aluminum) is in the pack, say whether color or sheen is judged on A-side only, and whether rack marks are allowed on a named B-side land. Splitting A and B after the model is already “all faces Ra 0.8” does not help unless you update the drawing. [Boss and rib notes](https://3dwk.com/resources/designing-bosses-and-ribs-for-cnc-housings) belong in the same pack when a rib sits on an A-side wall and would show through a thin cosmetic skin.
Aluminum 6061 bar/plate $/kg planning bands sit in the mid-commodity range under **rates.v1.1** material tables; material cost is rarely the face-class story—extra finishes, protective tape, and whether every wall is treated as A-side are.
Clamps, fixtures, and leftover witnesses
If B-side may show a vise or fixture witness, draw the allowed zone. If no witness is allowed on any face, expect a fixture, a sacrificial tab, or a secondary cleanup and a wider **rates.v1.1** estimate band. Do not leave “no tool marks” next to a deep pocket that can only be held from the cosmetic wall. Interior faces can be a third class (utility, as-machined) so the shop does not polish a hidden cavity that the buyer will never see. Related housing notes: [boss height and draft](https://3dwk.com/resources/boss-height-and-draft-notes-cnc-housings).
Tolerance and inspection traps
Calling “cosmetic all over” without an A/B map, mixing a tight Ra with a chem-film rack that has no allowed mark zone, omitting which edges are A-side, or asking for 100% visual under raking light on every interior wall, all force **needs_manual**. Default hidden walls to a utility class and put cosmetic inspection only on named A-sides. Related: [ISO 2768 general tolerances on CNC RFQs](https://3dwk.com/resources/iso-2768-general-tolerances-cnc-rfq), [surface roughness Ra callouts that raise quotes](https://3dwk.com/resources/surface-roughness-ra-callouts-that-raise-quotes), [how anodize choice changes CNC RFQ cost](https://3dwk.com/resources/how-anodize-choice-changes-cnc-rfq-cost).
Illustration 1 shows an **Example part** housing with a labeled A-side lid and a B-side clamp zone versus an unlabeled “all faces cosmetic” body.
Example part walkthrough
**Example part:** Aluminum 6061-T6 housing ~90×70×25 mm, face A a cosmetic lid wall at Ra 1.6 with no vise witness, face B a B-side with clamp witness allowed outside datum D, ISO 2768-m general. With STEP + **FACE A: A-SIDE, Ra 1.6, NO VISE WITNESS; FACE B: B-SIDE, CLAMP OK OUTSIDE D; INTERIOR UTILITY AS-MACHINED**, expect a usable automatic planning band on [quote-new.php](https://3dwk.com/quote-new.php). Same geometry with silent CAD and “no tool marks on any face” often lands DFM notes or **needs_manual**—without inventing any customer PO.
Illustration 2 contrasts a vague RFQ (“must look perfect all around”) versus a labeled A/B pack and the clearer estimate path.
What widens bands fastest
Every face marked cosmetic, clamp lands left unspoken, coating rack marks with no allowed zone, and 100% raking-light inspection of interior walls. Quantity breaks help unit minutes but do not erase face-class ambiguity—see [how quantity breaks change CNC unit cost](https://3dwk.com/resources/how-quantity-breaks-change-cnc-unit-cost) and [what needs_manual means](https://3dwk.com/resources/what-needs-manual-means-preliminary-quote).
What to do next
Mark each wall as **A-side**, **B-side**, or **utility**, name allowed witnesses and post-coat inspection, then upload on [quote-new.php](https://3dwk.com/quote-new.php). Service pages: [CNC machining](https://3dwk.com/cnc-machining-service.php), [materials](https://3dwk.com/materials.php). Treat **rates.v1.1** min/mid/max as estimates, not invoices. If the UI shows **needs_manual**, answer the face-class questions rather than forcing a fake firm price.
Common questions
Does A-side always need a tighter Ra than B-side?
Not as a silent default under **rates.v1.1** estimates. A-side often is tighter because it is seen, but a B-side sealing land can be the tighter face. Write the class and the Ra you actually need.
Can I write “no tool marks” on the whole housing?
Only if you accept fixture cost or a wider band. Most housings can allow a named B-side or interior utility class. “No marks anywhere” is a process request, not a cosmetic adjective.
When should I add a handling tab instead of allowing a B-side witness?
When every exterior face is truly A-side and a clamp mark would fail the visual. Draw the tab, the cutoff remnant, and whether a cleanup pass is included.
How should I judge color after anodize or chem film?
Say which faces are compared, under what light, and whether rack marks have a home on B-side. Leaving “color to sample” on all faces with no rack zone leaves the estimator guessing.