BIP39 printable tiles

prusaprinters

Don't trust - verify!A possible attack vector on common signing devices (hardware wallets) is a supply chain attack, such that the mnemonic phrases given to you are not really random and possibly even already known to an attacker. Once you send UTXOs to addresses derived from these mnemonics, the wallets can immediately be drained.A way to mitigate this risk is to bring your own entropy to the generation of the mnemonics. A common solution is using dice via Ian Coleman's implementation https://iancoleman.io/bip39/, also available via SeedSigner, ColdCard and others. However, you still have to trust the hardware to correctly turn the dice rolls into the mnemonic or at least cross-validate with another implementation.Completely trustless methods include coin tosses with eleven coins encoding binary numbers from 0 to 2047 and picking the corresponding words from the enumerated BIP39 wordlist, then adding the final (checksum) word with SeedSigner, ColdCard, or BitBox02 (or an offline computer running a secure Linux Live distribution). Another option is to print the BIP39 wordlist, cut it in pieces and draw the words from a hat, then calculate the checksum word. But be sure to mix very well before drawing, otherwise your randomness might end up compromised.Here, we have a 3D printable BIP39 wordlist! It comes on eight pages with 8x32=256 words each. The pages fit on Mini FDM printers with 165x165 mm² print beds and print with fairly standard settings and a 0.4mm nozzle. However, you need eight prints and that will take quite some time.A miniature version can be printed on 235x235 mm² print beds (Ender 3 style) in just two prints:Use Cura 5.0 or newer to benefit from the variable linewidth feature.Use a 0.3mm nozzle with 0.2mm layer height.Scale to x=66%, y=66%, z=50%.Arrange four pages with +-53mm shifts.Print at 50 mm/s, outer walls with 25 mm/s.Increase number of walls/perimeters so that no infill is generated.Disable combing.Set minimum linewidth to 0.24mm and adjust minimum feature size etc.Set linewidth to 0.33mm.Coasting might be necessary.Make sure the letters print with a single layer.This is tested on a modified Ender 3 v2 with dual z-drives and direct drive mod. The huge number of retractions and the detail required might be a problem with Bowden extruders, but I haven't tested this.After printing, throw the tiles into a hat, mix well, and draw blindly 11 or 23 words one after another (remember to put the words back!) and complete the mnemonic by calculating the final (checksum) word with SeedSigner, ColdCard, BitBox02, ….The Python code used for generating the pages using solidpython and OpenSCAD is included and can be freely modified!