Printable folded-cardstock nesting desk tray kit

Design Foldsmith, a finished printable fabrication kit for an adult maker: two small open-top folded-cardstock desk trays that nest for storage. Deliver dimensioned full-size SVG cutting/creasing templates in millimetres on separate A4 sheets, a printable PDF assembly booklet with numbered diagrams and a 50 mm calibration square, and a machine-readable parts/dimensions file. Choose feasible dimensions, cardstock thickness and assembly tabs so every piece fits within A4 with 10 mm print margins. Clearly distinguish cut lines, mountain/valley folds and glue areas without depending on colour. Explain clearances between nested trays and state which dimensions are nominal. Include a deterministic, offline geometry check with recorded results checking page bounds, non-overlapping parts, panel/tab counts and the claimed nesting clearance. The kit itself is the primary product, not a website or a report about making one. Use original designs and no external services. Do not claim a physical build or strength test happened. English deliverables; make reasonable reversible design choices independently.