ParaMat3D
Polymer-filament OpenSpool hardware v0.3 · closed-side first fit

One carrier.
A snap-on cover.

A parametric carrier and snap cover for the ParaMat bench reader: an 80 × 70 mm ESP32-S3 terminal adapter beside a PN532 V3, with a plain nonmetal RF path and service access for testing.

Download cover STLCarrier STLSee what still needs testing
Isometric line rendering of the first-fit OpenSpool snap cover
145.7 × 78.0 mmnominal footprint
180 × 180 mmA1 mini plate envelope
15 mmin-plane board gap
M2.5 × 6adapter screws

Designed around the assembled demo—not a generic ESP32 case

The 44-pin YD/AITRIP controller plugs into its green terminal adapter, so clipping the ESP32 PCB itself would obstruct the header rows. The current first-fit model mounts the adapter through four board holes. Short M2.5 screws form a light thread in blind plastic pilot slots; no nuts or heat-set inserts are required for stationary bench use.

Measure before the full print: the current 72.5 × 32 mm hole pattern comes from a published reference adapter. The actual AITRIP board's two center-to-center dimensions and hole diameter still need to be confirmed.

A clean, closed-side cover with bounded USB access

The separate inverted tray snaps around the existing printed carrier with four compliant side latches and a segmented edge groove. It uses no additional screws. Both long walls are closed. The short USB end retains its lower wall and a 2 mm center rib, with only two nominal 12 x 9 mm connector apertures centered at Y = -7 mm and Y = +7 mm. Their locations remain first-fit estimates relative to the provisional controller origin.

Two small top holes provide probe access to RST and BOOT. Their longitudinal positions come from the controller's 2.54 mm pin grid. The onboard RGB is covered by a 0.45 mm white-plastic membrane rather than a large opening. Control location, latch force, cable clearance, light diffusion, and RF performance remain physical-validation items.

Download the first-fit package

Start with the three small coupons. They turn printer and material tolerances into a cheap measurement before the full carrier and cover are printed.

Snap-cover STLRoof-down export; physical fit pending Snap-cover STEPAssembled orientation for CAD revision Cover latch couponTest one real latch against the carrier Carrier STLGenerated prototype; print coupons first Carrier STEPEdit in Rhino or other CAD Fit-check STEPCarrier, cover, and simplified envelopes PN532 clip couponTest clearance and flex first M2.5 screw coupon1.9 / 2.1 / 2.3 mm pilots CadQuery sourceDimensions remain parametric Build instructionsPrint, assembly, and RF checklist Release manifestInputs, hashes, and validation state Hardware licenseCERN-OHL-S-2.0 and scope notice

Print → fit → prove

1

Calibrate cheaply

Measure the adapter-hole pattern, then print all three coupons in the intended material. Confirm the screw pilot, PN532 clip force, and cover latch before a full print.

2

Assemble openly

Print the flat carrier in PETG, mount the adapter with four M2.5 × 6 mm screws, then install the controller and PN532. Use a brim if the long corners begin lifting.

3

Test the real system

Finish internal wiring, disconnect USB, and snap on the roof-down cover. Insert the intended USB plug or plugs through the two bounded apertures; then verify probe access, RGB diffusion, bridge quality, and NFC read/write beside the printer.

What the computer proved—and what it did not

Completed: the CAD generator produced valid carrier, cover, and coupon solids. Eight automated geometry tests cover declared board envelopes, reference mounting inputs, board separation, the 149.6 x 81.9 mm cover envelope, roof-down orientation, snap-groove inputs, closed-wall solid probes, dual-USB aperture geometry, and declared pin-grid control locations within the A1 mini plate envelope. These are computer checks, not physical-fit evidence.
Still pending: actual adapter-hole measurements, physical fit, connector access, and RF validation. Until the real print passes the checklist, this remains a first-fit prototype—not a claim that every reseller batch will fit.

Compatibility boundary

This is a mechanical carrier for an external PN532/ESP32 reader. It does not make a stock Bambu AMS Lite understand an NFC standard by itself. The current ParaMat browser writer creates OpenSpool 1.0 JSON on compatible tags; the bridge then maps supported data toward the printer. OpenTag3D is a separate encoding, and no native Bambu compatibility is claimed here.

The external OpenSpool Mini enclosure targets different controller hardware and is not redistributed here. This model is new CadQuery geometry derived from published board envelopes and mounting dimensions.

Design method

Published dimensions established the first geometry; the product photograph resolved orientation and access; the controller's 2.54 mm pin grid located the cover controls; RF constraints kept metal-filled material away; parametric CAD preserved revision speed; and automated checks rejected obvious plate, spacing, and envelope errors. The physical print now supplies the evidence that a screen cannot: actual shrinkage, latch force, connector reach, LED diffusion, and read range.

Copyright © 2026 Sunnyday Technologies. Covered hardware design files are released under CERN-OHL-S-2.0, which permits commercial use subject to its source and notice obligations. Files and resulting products are provided as-is and without warranty. Power off before assembly, prevent shorts, keep metal and wiring away from the PN532 antenna, and validate fit and radio performance before use.