Ask HN: What's the coolest physical thing you've made?

I built a super cheap "traditional" dry sauna. It's basically an electric burner, a pot to increase surface area and humidity, a 25 foot roll of thermal foil, and a sleeping bag as the ceiling. I disassembled the burner, removed all the plastic pieces, and short circuited the safety cutoff. It's jank AF, but in the end less than 100$. AFAIK there aren't any dry saunas under $1000 - the heater alone is ~$200. Mine is also portable, so it's in the garage in summer and in the laundry room in winter. There are portable infrared saunas for ~$100, but most studies are on the "dry" type. I rubber band a block of ice to my phone and do my reading/social media in there, so the time cost is reduced. It's pitch black in there, so I have a very bright night light. No problems with air circulation - it doesn't get stuffy, even when I throw a dash of water in the pot. https://i.imgur.com/Lml7Vms.jpg

2 years in and I haven't burned down the house... yet. I've since added more ceramic around the pot so burning myself would be very difficult.

(Reference to my post from the last time this article was posted on HN: https://news.ycombinator.com/item?id=28495062 )

I built a step stool that turned out really gorgeous. Walnut lumber, hand-cut angled dovetail joints. Plans were based on https://thewoodwhispererguild.com/product/dovetailed-step-st...

Although if you ask my kids, the answer would be their treehouse.

> Amazon doesn’t actually own data centers; similar to how they don’t own warehouses.

Are you certain they don't own at least a fraction of the facilities they use? Amazon has very good credit (AA or AA-), which in a lot of cases probably means they have access to cheaper money than their landlord does. When you factor in the landlord's profit margin, it just doesn't make sense for Amazon to rent rather than to issue bonds and buy.

I imagine that they do rent as well, since it lets them respond more quickly to demand / business needs, but it would just be really weird for them not to own any of their own critical infrastructure.

Edit: Looks like it's a mix of leased and owned, on both counts

https://www.datacenterdynamics.com/en/news/amazon-web-servic...

https://therealdeal.com/national/2023/02/07/amazon-slams-bra...

You don't need high heat (refractory) mortar for many outdoor fire pits or stoves.

It's mandated in many places (and for good reason) for indoor fireplaces, chimneys etc.

That's because regular mortar will crack when subjected to roaring fires, and you don't want the heat, fumes or fire itself to escape the chimney.

But e.g. for a fire pit it's usually no big deal, as the outside of the pit is presumably soil, or the open air.

Sudiball telescope mounts

I like visual astronomy and manual pointing (star hopping). Build a 12.5" Dobsonian (with Dobson) and it was great.

I also love doing public outreach (sidewalk astronomy). Wanted robust, portable, mount for larger mirrors. Ball scopes tick many of the desirable trade offs for me I put a 16" mirror in one and it was a favorite for years.

but balls do have drawbacks, lack of physical access to back of mirror, poor ventilation, how to lift into vehicle ... and they can be stunningly expensive to buy.

Sudiballs are my answer to how to easily construct precise light weight spherical analogs in the comfort of your own home with materials lying around.

HN crowd could likely think of them as wire frames of spheres in meat space.

There are of course many (infinite) ways to choose a wire frame representation of a sphere. So we choose one that provides convenience IRL.

The "wires" in the wire frame are the edges of some sheet material such as plywood cut into arcs.

By following the geometry of an octahedron, three planes (sheet material) intersect at right angles which (surprise) is exactly what our household tools saws, drills, routers, lasers etc, are designed to cut.

There are other details to make it work, ensuring the wire frame is always touching the base at least three points. Eroding the edges of the edges to be one with the sphere ...

But all doable by you.

[] https://ix.cs.uoregon.edu/~tomc/Hobbies/Astronomy/ATM/index....