I needed a door. It would have been 100$ to buy a 'colonial' piece of cardboard and MDF crap. I am an indifferent carpenter. It cost me 32.57$ and two hours work to build this from a piece of 58" spruce plywood and some pine one-side-planed 'barnboard'.

Yes, I'm proud.

"recursive Wang tiles" ... I think I want a box full.

This article on penguins using air bubbles to reduce their drag makes me think of the supercavitating torpedoes reputedly in use by the Russian Navy. Now, apparently part of the problem with the supercavitation approach is that its difficult to keep the torpedo traveling in a straight line, as the torpedo wobbles back and forth inside the large - and apparently irregular- gas pocket blown by the cavitation. If the penguins can make do with micro-bubbles, I wonder what the actual airflow rate would be necessary to lubricate an RPV...and if that amount of gas could be stored in a compressed cylinder on board. Will have to make some calculations. Hard part might be skinning the RPV with pores.

Recent events have made me aware of the amount of time I spend repairing my computers after virus & Trojan Horse attacks.
I've spent an average of four hours a month on these problems for the last several years: ever since I got broadband internet access, although I will admit the 'Net seems a lot more hostile than it used to be.
Extrapolating over forty years more the Internet use ( assuming, of course, that the Internet is still around in some form, forty years from now) means I'll expend 1920 hours. 1920 hours spent in 8-hr 'standard-working-day' segments is 240 days.
Twenty days short of a Standard Working Year.
I don't know what my yearly income will be in forty years, but I can guess that dealing with this bullshit is going to cost me the labor-equivalent of around
thirty thousand dollars.
In today's dollars.