I’ve been printing in my local region using a modified Up Mini since mid last year and with the advent of my December engagement combined with a recent community software upgrade for the closed-source Mini (FixUp3D); decided it was time to give myself a new challenge.
My Partner and I were in the midst of making engagement party invitations and realised although we had plenty of flair on our invitations, we weren’t too keen on having to write a return address on the back of each of 100+ envelopes, which is where the idea of getting a custom made stamp came up, and I realised I already had all the tools to make one for us. A 3D printer, some quick set silicone and the crazy eyed gaze of someone with a great idea.
I asked her to help find a design and some artwork for the banner and address, and with that created an SVG stencil I imported into Tinkercad, using it to design a mould for what would become the ‘rubber’ of the stamp. This was then printed on my trusty Up Mini with locally produced blue PLA at a 0.1mm z-layer height, 100% infill, 3 outer layers, no raft and a slower than standard print speed (for the Up this is not measured directly in mm/s or mm/min but I’ve included a copy of the config) to ensure the outlines would be as accurate as possible. It was also printed to ensure the recessed sections were facing up and avoiding any area requiring bridges or support, making for easier removal of the silicone later on.
After the mould was printed it was then boxed up in cardboard and the silicone mixed and poured in to set; leaving it for half an hour before painstakingly slowly peeling it off the mould, reaching in between the printed and silicone layer with a fine pair of tweezers to carefully remove sections that had wedged themselves into nooks and crannies.
Address is blurred out for our privacy sorry 
It took a few failed attempts getting the design and the height right, as there is a fine line between getting the detail on the printed mould too recessed to pull the silicone out without losing the finer thinner letters tearing off inside the mould, and making it too shallow to allow a defined stamp to be put on paper without transferring or smudging ink from the rest of the stamp but eventually we got there. A simple handle was printed and one of the old moulds was sacrificed as the base to which the silicone stamp was affixed.
The end result looked amazing and gave our invitations a special flair that wouldn’t have been possible without a 3D printer.
To top it all off, later that month I 3D printed 2 puzzles each with hidden message, inviting two of my best friends to be groomsmen at the wedding. But that’s a story for another time!
Andrew (Omegatron)
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Nikki
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@krusher, that’s really really cool. We’ve been playing around trying to get a good stamp printed and coated. Thank you for your insight. Might be back with a load of post weekend questions. 
Congratulations on your engagement and upcoming wedding!
Nice! This is a really cool project. Any tips on the mold? I’m doing something very similar for a stamp and the lettering height has been slightly off on first couple of attempts 
. I’m using Sugru - which is essentially silicone - and a negative.
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Has anyone tried using flexible filament eg ninjaflex for the stamp? Could be a handy seller.
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Hi Alex,
As noted I printed the original piece in PLA so didn’t have to worry about warping; the depth of the lettering and detail ended up being 1.4mm and I had to make the lettering as large (wide) as possible while being constrained to the size of the envelope, the minimum width of any feature details that came out successfully was 0.4mm
I’ve attached a close up of the silicone stamp showing just how well the silicone filled in every nook and cranny, so I would add that it’s important to make sure your top layers are getting good joins between lines and aren’t going to get anything stuck in there that will tear off your letting upon removal (which did happen on the first 2 tries!)
I hope this is helpful in your future attempts 
Hey Jamie,
I imagine it would be possible, however the reason I went with a mold to drop the silicone into is that it’s easier for mid-range printers to get a good quality outline of something (recessed into the plastic) than it is for them to do a fine top layer/thin wall.
Something like the wall/gap test print gives a good example of this, where printers without a fine nozzle will see spacing between the filament printed for the thinner walls, while the gap can be quite a lot smaller without lowering the print quality.
Very well done ! Thanks a lot for the sharing of your experience !
Left
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Very cool approach !!
Maybe it could help to sand the stamp a bit, so the letters are more even.
Defintly going to try this project myself
