Its my designe of a 2 by 2 Piston extender

at first i was a little bit lazy and wanted that other and better redstoner do it but i have done it alone so if you nothing to do make it smaller ^^

the obsidian is just a experiment but it works without using obsidian u can make it withe any solid block you want but you must keep the Glowstone because its awesome and this design needs it.

If you facepalm by reading this text sry i'm a German^^

ps. in the Schematic are 2 version one "nacked" version and a 90° rotated 2x2 Hidden door both are working