I just modeled this object that I'm going to be using in a bathroom. I tried importing it into Unreal Engine but when I do the mesh becomes black after light building. People said I have to create a UV lightmap so I looked up tutorials but first I need to UV unwrap twice since Unreal Engine takes the second UV as the lightmap. I have no clue where to start UV mapping since the urinal part dips in. I understand the top sensor part since its just circles and spheres, but its the other part I'm confused about.
Edit Mode: https://gyazo.com/ecbdebe1bdebc22820bbe4fab8123176
Here's a view from the inside: Object Mode:
Can someone please just say where I should mark seems?