Dear Frau Professor,
It was wholly a pleasure to hear from another shoemaker's child with an immigrant background, and to learn that a column about my father had struck "a personal note with me, having been raised by a shoemaker in Germany. Your article describes my old man par excellence, who now in his mid-70s and officially retired from his shop in a small town near Duesseldorf still repairs shoes for his customers."
Why, sure. Good shoemakers grow rarer and rarer, and those who have found one are well advised to stick with him - even though he claims to be retired. Just hand him a pair of shoes in need of heels-and-a-half-sole, and he won't be able to resist making them presentable again. It's a matter of pride.
Now on to your question: Is there is an English equivalent for the German phrase, zusammen schustern? You tell me it is used to describe slapdash work. As an equivalent, I'd suggest the English phrase, "cobbled together." I'd bet other languages have similar phrases, shoes being as ubiquitous in human cultures as feet.
The phrase may be a libel on cobblers of all nationalities, but one can understand how it came about: Cobbling can have the look of a make-do art, especially in cases where some emergency treatment is needed for a floppy sole or a broken heel, or if the customer can afford only half-soles or heels but not both.
I've seen my father study and study a pair of muddy old boots some poor sharecropper had brought in hoping against hope to save them for one more season. Finally, like a surgeon talking to the family in the waiting room, he would deliver his verdict - good, bad, or We'll Give It a Try.
The old man would take me with him some Sundays when he'd drive all over the Ark-La-Tex - to little towns like Longview and Tyler and Lufkin in East Texas, or to Ruston and Minden in the other direction, or up to Magnolia despite the condition of Arkansas roads back then.
The trunk and back seat of the old Chevy would be packed tight with just-fixed shoes. He'd show them to fellow members of the guild as samples of what he could provide if they were interested. And they were. Because there was a war on, and it took ration stamps to buy a pair of new shoes - but not second-hand ones. It was a sellers' market.
There was a Walt Disney comic circa 1944 that had Donald Duck on the cover in a cat costume; Donald was sitting on a backyard fence in the middle of the night and howling - so the neighbors would throw their shoes at him. He was collecting them for resale in a box labeled: SECOND HAND SHOES - NO RATION POINTS. Nobody had to explain that cartoon to me.