An idea that I have seen that I agree with is snap-to placement on the anvil so ingots don't fall of so easily.
Another one that i've been thinking of is add a small town around the shop where you can go out and buy ingots and handles from physical stores so you don't just order them from a screen behind the building.
Besides that fun little game, look forward to future updates. :)
(Just found the Trello page so nvm on my town idea XD Now that I see what you have planned for it I'm very excited for its future)