Edit the postcard.3mf, print it and send it, or read my article to learn more about how to create your own 3D-printed postcard.
They shipped without any issues from the Czech Republic and arrived both domestically and to the USA.
The text and pictures are easily exchangeable picture, it is designed to be printed in two-three colors on a single-extruder printer. The filament change will be done manually by you, the printer will prompt it.
The 3mf files have all the settings, you can just open them in PrusaSlicer, change the text/picture contents, slice, and send the G-code to your printer.
The file is set to having three virtual extruders - meaning three different colors. But in the end, it's up to you, which filament color you load into the printer.
In case you change the printer, or you think you might have accidentally changed the settings, here's what's necessary to make it work:
Or read the article where I give detailed instructions.
The secret message postcard (the one addressed to Sherlock Holmes) works on the same principle, but the text is hidden inside. It is only in the middle layer (0.2 mm height, 1 mm thick postcard, sliced on 0.2 mm profile) and I printed the postcard in Prusament Pristine White and the text inside in Prusament Vanilla white. This way, you can read it against a strong light, but otherwise it seems that the postcard is empty, just with an address on it.
The author marked this model as their own original creation.