Turns out it'd be a dissapointingly small sphere:

US annual defence budget = $800 billion

2% = $16 billion

Obsidian cost per kg = $5

Total kg in budget = 3.2 billion kg

Density of obsidian = 2.6 g/cm3 = 2600 kg/m3

Total volume of sphere = 3.2b/2600 = 1230769 m3

Volume of sphere = 4/3 π r^3

Radius = (3V/4π)^(1/3) = 66.48 m

The sphere would only stand at 133m tall, I propose we instead utilise the entire defence budget for a much more skyscraper like 490m tall orb

I've also got a pinetime watch, never been a fan of the data collection smartwatch companies do, its great to have something that I know exactly how it works with its open source firmware. It's not exactly perfect but there's been tons of updates from contributions by the community, I've even been able to make some modifications of my own too.

If anyone here in the comments has any questions about it I'd be happy to answer them

You can try walk up the hallway but you'll just find yourself walking endlessly unless you have at least 70 sysadmin stars

Thanks this will save me a lot of money

I run a patched version of the Infinitime firmware that has some tweaks to optimise battery life, these will likely be in the main release soon enough. I did a test after installing the firmware and got 10 days battery life from 100% to dead of daily normal watch use. This is with a somewhat new (~2 months old) watch so don't know how it may degrade but getting over a week is easily achievable on the pinetime.

No microphone unfortunately, it's a feature I would've liked but at least that guarantees it's not recording you