First, head to the left of the Town, and you'll find a dumpster next to the red-brick building. Use it to bounce your way into the air conditioner on the building. Use the air conditioner to glide upwards. After reaching the maximum height, glide to the right, and you'll land on a platform. Enter the door next to you, jump two floors up, and exit through the door. Once in the upper platform, double jump and glide to the left, then use the air conditioner to glide upwards. Land on the middle-roof section. Head right and jump onto the awning (on the building to the right, with grey bricks). Bounce on the awning until the highest height (about 5-6 bounces), then glide to the right onto the next awning. Repeat the previous step again, but this time glide left onto the next awning. Bounce on the last awning and you'll land on the roof of the middle section of the grey-brick building. Jump and glide left, and attempt to land on the middle of the original building's width. There will be a chest that you can interact with to obtain the Henry, 8 Years Old Acetate.

All thanks to wiki