Seed Phrase Stamping Jig 4 Words Per Washer

I liked the classic DIY washer seed phrase metal storage idea, but wanted something more compact and better looking so I designed this jig.

To reduce the overall size, the obvious approach was to fit more words onto each washer, and this jig does exactly that. By maximizing the usable surface area, this jig allows you to stamp four words per washer instead of just one, reducing the total from 24 washers (one per word) to just 6 for 24 word seed phrase.

This design takes advantage of the BIP-39 seed phrase standard, since no two words share the same first four letters, you only need the first four letters of each word for unique identification.

Each washer holds a total of 24 stamped characters: 8 digits used for word indexing in fixed two digit format (01, 02, 03, 04) to preserve order, and 16 letters representing the seed words (4 letters per word), resulting in a compact encoding like:
01just 02fury 03inqu 04flui

Required materials

• M8 × 24 × 1.8 mm washers

• 3 mm metal stamping letter and number set

To finish the assembly, I used an M6 sleeve nut and matching bolt (8 mm outer diameter, 10 mm length) to compress the washers into a clean, solid stack.