where is the arch object in waterpark world roblox

The arch object in Water Park World is part of the Design building options, alongside paths, terrain, walls, roofs, stairs, windows, and doorways.

So in-game, look under the Design tab when you’re placing build pieces. If you saw it in a video or guide, it was likely being used as a decorative or structural piece within that menu.

Quick location

• Open the building menu.
• Go to Design.
• Check the sections for structural pieces like walls, roofs, stairs, and decorative arches.

Note

The search results I found were limited, so I can only confirm that the arch belongs to the Design category, not its exact position in every version of the game UI.