▁order ▁to ▁make ▁Bell ' s ▁office ▁sound ▁like ▁multiple ▁layers ▁of ▁glass ▁and ▁bell ▁sounds ; ▁he ▁referred ▁to ▁the ▁scene ▁as ▁" a ▁little ▁o min ous " ▁but ▁not ▁" to o ▁c liche ". ▁ ▁Prop ▁master ▁Rob ▁Smith ▁joined ▁the ▁series ▁during ▁its ▁second ▁season , ▁and ▁had ▁to ▁quickly ▁learn ▁about ▁all ▁the ▁g ad gets ▁featured ▁in ▁Fr ing es ▁debut ▁season . ▁Smith ▁was ▁asked ▁to ▁create ▁a ▁" ne ural ▁stim ulator " ▁in ▁the ▁script ▁to ▁" M oment um ▁De ferred ", ▁but ▁" did n ’ t ▁really ▁know ▁the ▁episodes ▁well ▁enough ▁to ▁say , ▁‘ Oh , ▁ok , ▁that ’ s ▁exactly ▁what ▁it ▁is .’ ▁So ▁I ▁talked ▁to ▁the ▁director , ▁who ▁had ▁been ▁on ▁season ▁ 1 , ▁and ▁he ▁goes , ▁‘ Oh , ▁I ▁don ’ t ▁know , ▁it ’ s ▁just ▁something ▁that ▁goes ▁on ▁the ▁gu y ’ s ▁head ' ." ▁Smith ▁discovered ▁that ▁the ▁head pie ce ▁in ▁question ▁had ▁been ▁r ented ▁during ▁the ▁first ▁season , ▁causing ▁him ▁to ▁re create ▁the ▁prop ▁over ▁one ▁week end . ▁He ▁called ▁this ▁process ▁" a ▁little ▁bit ▁stress ful ." ▁The ▁g ad get , ▁Smith ▁explained , ▁was ▁important ▁because ▁it ▁" defined ▁the ▁way ▁that ▁Walter ▁works . ▁He ’ s ▁this ▁mad ▁scient ist ▁who ▁takes ▁conventional ▁science ▁and ▁then ▁puts ▁his ▁own ▁tw ist ▁on ▁it , ▁as ▁it ▁were . ▁And ▁then