Print the cards

Four cards: three numbered progression cards and one annex. Each one leaves you able to solve a cube, and each says on its own back what unlocks the next.

1. Print the set

Two-sided instead? Pick the file that matches your flip setting.

There is deliberately no single file that works under either flip. The numeral on both faces is your check — cut one card first and make sure its front and back agree.

Or reprint one card

2. Print at 100 %

This is the one setting that matters. Never “Fit to page”, “Shrink oversized pages”, or “Scale to fit”. Each sheet carries an 80 mm calibration bar in both margins — measure it after the first page. If it isn’t 80 mm, the scale is wrong and the card won’t fit a wallet slot.

Acrobat / ReaderPage Sizing & Handling → Size → Actual size. Turn off “Auto portrait/landscape”.
macOS PreviewScale: 100 % radio button (not “Scale to Fit”). Pick A4 / US Letter, not the “borderless” variant.
Windows / EdgePage Sizing → Actual size.
ChromeMore settings → Scale → Custom → 100. Its “Default” silently shrinks. Prefer another viewer.

Check your printer driver’s own dialog too — a driver-level “Fit to Paper Size” overrides whatever the application asked for.

3. Folding and two-sided

The default files are single-sided: print, crease the grey line, fold so both printed faces are outward, glue, then cut both layers together. That removes duplex registration error entirely, and works on printers with no duplex unit at all.

If you do want two-sided, the set ships one file per flip direction. Each card carries its number on both faces, so a wrong flip is caught after cutting one card instead of after wasting the sheet.

4. Paper and finishing

160–200 gsm feeds through most home printers. Cut on the grey hairlines — they run the full sheet, so one straight cut serves four cards.

A standard 54 × 86 mm “credit card” laminating pouch leaves about 0.4 mm of total clearance and will not seal. Either keep it wallet-sized and don’t laminate (the folded 200 gsm card is stiff enough), or use a 60 × 90 mm business-card pouch and accept that the result no longer fits a wallet slot.

Also on paper: the full PDF guide.