To my knowledge it was a chrome pinball by wardy91, but I could also be wrong. Milestonebarn is the right name for the one who release the first Custom Object for Planet Coaster. Congrats. And I tink, this was No.2 - relased just a half hour later:If I recall correctly, the very first custom scenery in RCT3 was either a box or a barrel, and look where that led...
Congrats to Millstonebarn for taking the first step, I hope it will be just the first on many!