what's he building in there?

Willie, my cat, is building something in there. Having burrowed into the box spring on the king sized Hemingway Sleigh Bed and following much clamor and banging I began to notice receipts carefully stacked next to the headboard. Lowes, Home Depot, Bed Bath and Beyond. Then it was thick carpenters pencils and cans of paint.
I began to wonder: what's he building in there?
Last night I saw flashes of light and a smell of sulfur that suggested welding. I looked for but did not find welding gear. Willie had a tell-tale fur burn on his right rear paw. And there was another on the carpet - not a cigarette burn, I quit last November.
Today, when I arrived home from work, an attractive young tabby slipped through the garage door before it shut. I opened the door to the laundry room and the tabby shot past me and straight up to the loft. I heard a crinkle and a pop and upon investigation found evidence of crackers and white sparkling wine. That's when I noticed Willie had apparently hung a tiny, neon "No Vacancy" sign. Around 7:00 PM the tabby began mewing at the front door and I let her out. I heard the upstairs shower fire up and Willie came down shortly after in what appeared to be a silk kimono. He smelled strongly of my missing bottle of Calvin Klein.
I went upstairs with a flashlight but the evidence was gone. The No Vacancy sign had been switched to Vacancy. A small group of immigrant landscapers were carefully tending to the carpet and the false potted plant out front. I sat on the edge of the bed and wondered aloud, "What's he building in there?"