Payap scenario: parametric BIM model of the whole plant on a square plot

A separate FreeCAD 26.3 model (the Mueang Chi model is untouched) sites
the plant on a 110 m square placeholder plot of Payap land, built from
BIM objects (Arch Site, Buildings and Levels, walls, slabs, columns,
beams, a ramp, Spaces with computed areas, Equipment). Every object sits
on an expression-driven base, so the Params sheet drives plot, setbacks,
floor level, building sizes, fire wall line and office gap (checked:
plot 110 to 120 m and factory 84 to 90 m, everything followed).

- Factory 84 x 25 m, production only, in process order along a 54 m
  glazed corridor; press hall 465 m2 with the October fleet (two Duplex
  systems, each EX 50 + EX 35, and the Classic); crane to the fire wall;
  machine door and 12 m ramp at the north-west corner.
- Office building 24 x 15 m, 12 m away on its own slab with a covered
  link: reception, offices, meeting/training, mastering and cutting,
  listening, IT, archive. Resolves the crane-zone conflict of the old
  sketch.
- Utility yard behind the press hall (boiler and chiller flagged for
  re-sizing), gate, truck apron, car park, service road.
- site-candidates: new section and plot-fit note; crane doc: conflict
  resolved, 54 m corridor; README bullet and layout lines; the old
  sketch is labelled as Mueang Chi with the earlier fleet.

docs/site-candidates.md

@@ -86,7 +86,9 @@ pharmaceutical facility on the offered land is to be confirmed.
    above ground for the loading docks, helps but is not a flood
    assessment.
 5. **Plot fit.** Shape and size against the 60 × 25 m building, the
-   detached utility yard and the phase 2 footprint (6 to 8 rai).
+   detached utility yard and the phase 2 footprint (6 to 8 rai). The
+   Payap scenario model below fits the whole plant on a 110 m square
+   (7.6 rai) as drawn.
 6. **Galvanics on a campus.** Phase 5 electroplating needs the lessor's
    written consent; the zero-discharge design
    ([sustainability](sustainability.md)) becomes a lease condition, not
@@ -102,3 +104,64 @@ Nothing has been re-sited. The parametric model, PV roof study, RFQ and
 the fleet site code `lpn` in the [digital factory](digital-factory.md)
 stay on Mueang Chi until a Payap plot is known and has passed checks 1
 and 2.
+
+### Payap scenario model (October 2026)
+
+To see the plant on Payap land before a plot is known, a separate
+parametric BIM model sites it on a simple square plot:
+[cnx_vinyl_parametric_payap.FCStd](cnx_vinyl_parametric_payap.FCStd)
+(top view [PNG](cnx_vinyl_parametric_payap.png),
+[isometric](cnx_vinyl_parametric_payap-iso.png)), built in FreeCAD 26.3
+from BIM walls, slabs, columns, spaces and equipment. Every size and
+position hangs off its `Params` spreadsheet (plot side, setbacks, floor
+level, building sizes, fire wall line, office gap), so the square can be
+swapped for the real plot once Payap names one. It is a layout sketch:
+every position and every equipment envelope is an estimate.
+
+- **Plot**: 110 × 110 m (12,100 m², 7.6 rai, inside the 6 to 8 rai of
+  [scale](scale.md)), road assumed on the south side, 6 m setbacks
+  (placeholder).
+- **Factory, production floor only**: 84 × 25 m at floor level +1.2 m,
+  in process order along a 54 m glazed visitor corridor. From west to
+  east: staff entry and lockers; workshop and spares, with the machine
+  door and a 12 m vehicle ramp at the north-west corner; galvanics clean
+  room and water treatment; stamper prep, PVC lab and material area;
+  compressed air and electrical; the press hall; trim and optical
+  inspection, QC lab, and finishing and packaging. Behind the fire wall
+  at 62 m are the warehouse and dispatch with two dock doors.
+  - The press hall (465 m²) holds two Duplex systems, each two HRP 12
+    presses with an EX 50 and an EX 35, and the Classic
+    ([pressing line](equipment/pressing-line.md)).
+  - The 5 t crane runs from the west wall to the fire wall
+    ([crane, workshop and tours](crane-workshop-tours.md)).
+- **Office building, isolated from the factory floor**: 24 × 15 m, single
+  storey, 12 m south of the factory on its own slab and structure, joined
+  by a covered link that lands at the start of the visitor corridor.
+  - It holds reception, offices, a meeting and training room (the
+    [Payap programmes](payap-partnership.md)), mastering and cutting with
+    an inner acoustic lining, the listening room, the IT and server room,
+    the archive, and WC and kitchen.
+  - The lathe sits away from press vibration and outside the crane zone.
+- **Utility yard** behind the press hall, across a 6 m service lane:
+  - boiler house with chimney and a covered fuel store;
+  - chiller and cooling tower;
+  - process and fire water tanks;
+  - PEA transformer;
+  - a pipe bridge to the press hall.
+
+  Boiler and chiller are drawn at the one-Duplex sizes and need
+  re-sizing for five presses ([scale](scale.md)).
+- **Access**: one gate on the south side opens onto a truck apron in front
+  of the dock doors, with the car park in front of the office and a
+  service road round the east end to the yard and the ramp.
+- **Area**: about 2,100 m² of factory plus 360 m² of office, so ~2,460 m²
+  under roof. That is above the 1,400 to 2,000 m² of the [scale](scale.md)
+  zone table, which held one Duplex and an automated zone with the offices
+  inside.
+  - The press hall matches the new fleet.
+  - Warehouse and dispatch (~530 m²) are drawn above that table's 300 to
+    500 m² for packaging and finished goods.
+
+  Both are estimates to settle against the real plot.
+
+The Mueang Chi model and everything sited on it stay as they are.