Just made this small tileable triple vertical piston extender. (Don't know if it's been done before, didn't check, but this is what I came up with.) : r/redstone
(1x9x9) 1-Wide Vertical Triple Piston Extender: Tile-able & Flush-"ish" - Redstone Discussion and Mechanisms - Minecraft: Java Edition - Minecraft Forum - Minecraft Forum
Movable, vertical triple piston extender made entirely from solid blocks! : r/redstone