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

My MIL is 93, and the only tech she can really deal with is turning on the radio and TV and changing channels.

She is fond of music from old classics (from the 60's and earlier), so I hooked up a Raspberry PI with an FM transmitter and created her own private radio station. She tells me what songs she likes and I create different playlists that get broadcast on her station. It preserves the surprise element of radio, and there is nothing in there she doesn't like.

The tiny FM transmitter is surprisingly powerful. Her neighbours (of similar vintage) are very happy too, so their requests have also started coming in :)

EDIT: I wanted to add that I am the UI ... she doesn't get to choose the playlist. To make my life easier, I just created different playlists for different times of the day ... calm/spiritual/slower numbers in the early and late hours, peppy during the late morning and evening etc.

OP seems from India and AFAIK its illegal to transmit on FM frequencies without a license. I understand it might be low powered but theres a chance of Police coming knocking on the door. Whats worse is it might interfere with emergency services. There is a reason we have spoctrum licences.