Handmade Soundproof Room (Maybe good for practicing karaoke while having a drink with a small table)

For sale to those who enjoy DIY assembly.
⭐️ Size
External dimensions L x W x H (mm)
2,240 x 1,770 x 2,095 (exterior is a steel storage shed) including roof overhang
Internal dimensions 1,950 x 1,250 x 1,740
It's quite spacious.
This is a handmade item I created about 30 years ago, based on a steel storage shed and finished with tatami mats and materials from a home improvement store.
Soundproofing performance that rivals expensive brand-name products! Possibly even better than brand-name products?
It was installed in a 4.5-mat room on the second floor of an old wooden rental house, but it has now been dismantled.
⭐️ Soundproofing is fundamentally about weight and thickness. It's said that tatami was used in the early studios of Tokyo University of the Arts.
Even when I was struggling financially, I practiced playing wind instruments at home.
⭐️ I used it as a practice room for my saxophone, but it became unnecessary after I suffered a stroke and became paralyzed on my left side two years ago.
I listed it on Mercari once, and a buyer was found. They inspected it, tested the soundproofing, and were satisfied. However, after the entire dismantling was complete, they canceled, saying, I'm not good at DIY and I'm worried I won't be able to assemble it properly. I'm not a carpenter, and I don't think it's a difficult construction, so I'm relisting it.
I want someone who enjoys DIY and will have fun assembling it with their own modifications to purchase it.
⭐️ If you plan to transport it yourself, you will need a vehicle with a cargo space comparable to a Hiace.
I have drawn diagrams to help you load it in one trip. (20 steps, 9 pages)
If you plan to use a shipping company, please arrange it yourself.
⭐️ When I first listed it, I thought taking photos during disassembly would make it easy, but I have drawn detailed assembly diagrams so anyone can assemble it. (33 steps, 22 pages) Assembly might take over 10 hours for one person?
There will be some expenses for decorative sheets for the plywood and electrical cables, etc.
⭐️ Soundproofing Performance
When the audio volume is at maximum and you go outside, it feels like you're just listening to a CD in a normal room.
⭐️ Features not found in brand-name products
There are 6 external terminals, allowing you to connect with cables and enjoy jamming with an electric guitar or keyboard outside the soundproof room using headphones.
⭐️ Equipment such as the keyboard and recorder shown in the photos are not included.
⭐️ Process until transaction completion
1. Purchase
2. I will mail the assembly diagrams and my address/phone number.
3. Contact me via SMS with your phone number.
4. We will coordinate via SMS and phone.
5. Pick up, assemble, and leave a review.