Cz furnace for crystal growth, or an open source curve tracer and semiconductor parameter analyzer.

But I think that right now the cost of materials is just to high, even outside of tech.

The cost of metals, cement, and power can be heart stopping for the younger folk.

- An entirely self contained DNA analyzer that has no ability to communicate with anything except for a USB thumb drive that it writes plain text files to. It must have more self contained knowledge than all the commercial test sites combined. Bonus if it understands all known human genetic defects. Extra bonus if it also understands all the minerals, vitamins, enzymes, hormones and how those effect the epigenome. Extra Extra bonus if it has a camera that can "see" all the electro-chemical bonds in tissues to detect cellular errors before they are otherwise detectable. Yes, a tri-corder except better than the fictional tri-corder.

- A bog-standard ARM or x86_64 cell phone that loads all its kernel modules from a bog standard Linux installation any distro, standard LTS kernel and every module including that which drives the modem has been reviewed and approved by Linus without ever once tempting him to raise the middle finger or start writing an email. Bonus if the modules are all written in Rust and written good enough to impress all the developers. Extra bonus if the powered on standby time is 3 months. Extra extra bonus if most of the parts are user serviceable, especially the battery and modem so that phone can evolve with the LTE and Wifi standards.

- An electric car that has 100% user serviceable parts, no dial home upgrades done via USB and prompted by owner, no surprises. It must not be much more complicated than a golf cart and yet passes all regulations. 20 year bumper to bumper guarantee backed by the local government in case the business goes under. 2000 mile range 3D printed solid state battery with battery swap stores all over every country. Call it the Ford Model E=mc^2.

- User programmable nannites that can be swallowed without stomach acid harming them and they repair all forms of damage known to science, continuously for 1000 years. Programmable function include the ability to remove genetic defects and add new genetic traits. Easter egg functions include forcing the user to pass gnarly gas when they are around someone they dislike.

- A "sleeve" that can back up a human similar to the movie Altered Carbon and restore them to a new body when their body takes too much damage. If the person has a trait that conflicts with societal laws, they can choose to have that trait stripped from the backup at a super-genius store. Traits and knowledge can also be added for a cost, of course.

Home camera. Probably does, but not easy to set up.

Tablet that reads text-to-voice using local AI. Download a .txt book or a PDF and it reads it to you.