Finger strength training w/ no hangboard

I cant hang a hangboard where Im living and will be moving too soon to justify buying one anyways. The closest gym is an hour away so Im looking for ways to build finger strength without a hangboard. Some of my door frames are good to hang from but any other suggestions would be appreciated

I bought some rock rings, and I use them to lift weights or furniture.

Rice bucket a la "The Way of The Iron Fist"

https://www.youtube.com/watch?v=dhNDPD4gxpc&spfreload=10

Would this work for you? blankslateclimbing.com/

Hangboarding is by far the best way to get strong fingers so, hopefully the blank slate setup will work for you...

Heavy finger rolls with a bar and weight, make yourself some pinch and crimp blocks.

stevemaischtraining.com/cli…

that has some crimp block work.
Basically these can be made with a few dollars worth of 2x4's, screws and 1x2's. you also will need some accessory cord and weight plates, but those are usually easy to find cheap or free on clist