For years I kept my solder sealed in a plastic jar with a small hole on the side. I've created this relatively easy to print solder dispenser only requiring a 16oz plastic jar from amazon. Use the short spool holder If you don't want to drill a hole in the top of the jar or would rather a better seal. 

Jars from amazon: 

https://www.amazon.com/gp/product/B07TP6XGYD/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1