To　reduce　the　SF6　usage　as　well　as　the　material　and　space　costs　in　gas　insulated　switchgear　(GIS),　compact　GIS　devices　with　downsized　solid　spacers　is　urgently　required.　In　this　paper,　a　tool　chain　for　the　design　and　prototyping　of　compact　GIS　basin　spacer　is　proposed.　Firstly,　the　concept　of　geometrical　optimization　and　functionally　graded　materials　is　combined　to　design　compact　GIS　spacers　with　significantly　improved　surface　electric　field　distribution.　Then,　hollow-structure　3D　printing　is　integrated　with　vacuum　infilling　to　build　downsized　(10:1)　prototyping　550kV　spacer　with　both　optimized　structure　and　permittivity　gradients.　Experimental　results　indicate　that　the　surface　flashover　voltage　can　maintain　the　same　level　in　the　10:　1　prototyping　insulator　under　0.1　and　0.2MPa　SF6　gas,　even　with　10%　reduction　in　outer　tank＇s　diameter.　Therefore,　the　effectiveness　of　proposed　tool　chain　is　verified　for　the　development　of　compact　GIS　spacer.　©　2022　IEEE.