Answer:
由 YUU, YU, YUI, yoshi - reason, cause
同 DOU, TOU, ona(ji) - same
固 KO, kata(i), kata(maru) - hard, harden
間 KAN, ma, aida - interval, between
工+凡+木 KOU, KU - artisan, skill, work / BON, HAN - common, ordinary / MOKU, BOKU, ki - tree
Add 竹 (CHIKU, take - bamboo) and watch new kanji shoot out from them!
笛 TEKI, fue - flute, whistle
筒 TOU, tsutsu - pipe, tube
箇 KA - counter for objects
簡 KAN - simple, brief
築 CHIKU, kizu(ku) - build, erect