From Applied Science.

A new desktop SLS nylon 3D printer can make printed electronic circuits with the addition of a powdered catalyst and electroless copper plating bath. The printer is available here: https://www.kickstarter.com/projects/micronics3d/micron-a-desktop-sls-3d-printer

Applied Science video on SLA printed circuits: https://www.youtube.com/watch?v=Z228xymQYho

Favorite copper plating bath recipe:
Heat 250ml deionized water to 60*C in a 300ml beaker, stirring at 350 RPM
Add 2.5g CuSO4*5H2O, wait until dissolved
Add 4.6g EDTA disodium dihydrate, wait until dissolved
Add 0.84ml of 1% Triton-X 100 solution in water
Dissolve 5.8g NaOH in 30ml DI water, stir until clear, then add to bath
Add 4ml Formaldehyde (37% HCHO)
Lower stirring to 100 RPM and begin filtration with 0.5 micron syringe filter and peristaltic pump. No intentional oxygenation or bubbling. Filter return is below surface for minimal splashing.

I experimented a little with PEG and 2 2′ Bipyridine, but didn’t find them impactful enough to discuss in this video.

LED rectenna designs:
https://josepheoff.github.io/posts/1-hatband
https://www.nrl.navy.mil/STEM/LEctenna-Challenge/

Electroless copper references:
https://www.nmfrc.org/pdf/p0295g.pdf

Copper chromite catalyst:
https://www.sigmaaldrich.com/US/en/product/aldrich/209317
Possibly available here: https://www.kremer-pigmente.com/en/shop/pigments/pigments-of-modern-age/spinel-similar-pigments/47420-spinel-black-no-42.html It’s been backordered for a month, so I wasn’t able to test it.

Open Sauce 2024:
https://opensauce.com/

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https://www.patreon.com/AppliedScience