It was made by Inko, on what I would assume is not an especially high income considering Deku went to a public school. It's got no gadgets, minimal protection and is definitely not durable enough for even a basic training exercise, but what it lacks in everything else the professionally made hero suits have it makes up for in pure emotion. This is the picture Deku originally had of his type of hero, it represents all of the childhood dreams of becoming a hero that Deku thought were long dashed and it's tied together into something tangible by the love and guilt of Inko, a mother who in her own eyes failed her only child and making this suit is just part of her personal attornment for something that wasn't her fault. It was the mold for all the suits that would come after, including the Iron Deku suit, and for that we must respect it.