Even if they made a house out of toy blocks, there is no one that would think that they made a real castle all by themselves.
To make an original magic device, he would need high-grade materials, magic knowledge, lots of money, and plenty of time.
There are lots of stories of magicians destroying themselves, and countries depleting their treasuries in order to develop a magic device, and yet…
Lute-kun who was smarter than me should have known this.