Ask HN: Most interesting tech you built for just yourself?

I have glued BLE beacons onto my trash cans in the backyard and written a Python program for a Raspberry Pi that uses its Bluetooth interface to detect the beacons and keep track of whether they are present or not. It also downloads the trash collection calendar from the local utility provider responsible for collecting them and produces an overview over all four types of trash cans with info on their whereabouts (in the backyard or next to the street, based on whether the beacons are visible or not) and number of days until they are collected. If collection is imminent (tomorrow) and the location is still "the backyard", a big flashing warning is shown, requesting whoever reads it to move the trash can to the street so it can be collected.

The Python program produces a regularly updated XML document, which references some XSLT so that when it's loaded in a browser it'll render a nice HTML page with styling and images and stuff. The Raspberry Pi serves that over an HTTP server in the local WiFi, and in the kitchen there's an old Amazon Fire 7 tablet stuck to the wall where a Kiosk browser keeps that page on fullscreen display and regularly updated. The tablet also has all sleep modes deactivated so it is on all the time.

This way we never forget to move out the trash for collection, which we did regularly before I had this solution in place (built it about 5 or 6 years ago). It's horrible in a family of four if the trash is overflowing just because you forgot to move the trash cans to the street so they can be picked up.

2 years ago the solution (called "Internet of Trash") was extended by a little Bluetooth label printer located next to the tablet in the kitchen and some UI on the web page allowing to quickly print sticky labels with two lines of text, usually used to label boxes with food leftovers and pre-cooked ingredients (such as sauces for example) with what's in the box and the date when it was cooked. The UI has easy quick-choice buttons for the common food items we usually have and the last few days for the second line, but also allows free-form entry. It relays all input via the Raspberry Pi which sends it over Bluetooth to the printer. The labels help us immensely to keep track of leftovers stored in the fridge or the freezer - not just to know the exact type of food in the boxes, but also to determine when stuff has to be thrown away or which to use first when multiple boxes contain the same food ingredient.