Warhammer of zillyhoo

I plan on cosplaying Gamzee Makara at CAD and want a warhammer of zillyhoo to go with the cosplay since he has been cannonly shown weilding it while sober (albeit for like 3 pages as far as I remember) Does anyone have any tips about how to make one? and people that have brought warhammers of zillyhoo before, were you allowed to keep it or did you have to return it to your car?