I used to do quite a bit of craft wholesaling as well as retail at some of the better juried shows, not in metal - in hand blown glass, but I believe the principles are fairly similar. I did both the ACC and Rosen wholesale shows, which, at the time, were arguably some of the better avenues to approaching the wholesale craft market. At the time internet sales of fine crafts were still in their infancy, and the relatively recent upsurge in fine craft sales online may have changed things. Typically my annual revenue was split about 50% for each of retail and wholesale. A couple of things I learned:
You can not price your retail work below what the gallery sells those items for without risking loosing those clients. The difficulty is that while many galleries adhere to a double markup, some have triple markups, and some give fairly deep discounts to their professional clients (designers) or offer periodic sales. This can make it a bit difficult to price your items for the retail market. One potential solution is to have a completely separate line that you only sell at retail shows (also works for hitting those lower price points that work well for impulse buys) with a couple of larger attention getters at the full double wholesale price.
Make sure you include the cost of the wholesale show fees (space fees, booth [design, construction, maintenance, lighting...], travel, literature, lodging, food...) in your wholesale pricing. You will be surprised at how much it costs to put together a professional display.
Your display must be very well designed, easy to setup and well lit. Having good quality video showing the processes is a great draw (both for retail and wholesale). Another tip is to have large scale photos on display of your work (especially if it is small and intricate). The wholesale shows are typically very large, and buyers have a lot of ground to cover, anything that will attract them into your booth is a big help.
Keep your booth area clean, the more professional the better clients you will get.
Don't over pack your display, leave enough space between pieces to let the buyers see them and imagine them in their own galleries (where they will most likely be packed into displays with other work, but let them dream...)
If you use the same booth design for your retail and wholesale shows expect to have to upgrade/rebuild much more often. You may want to rent booth equipment for the wholesale show instead.
Doing full out production on smaller items for wholesale clients is brutal and somewhat thankless. As previously mentioned attempt to tool up to "automate" as much of the labor for this as possible. My experience is that is was hard to make minimum wage blanking out smaller production items.
Be very organized in taking orders from galleries. Getting triplicate forms is cheap at places like Kinkos, and having a signed order form can save a lot of questions later down the line.
Fill out a central production schedule as you take orders, nothing is worse for a new client than not being able to meet a deadline you have promised.
Have something for the shoppers to take away with them. A wholesale price list and drawings or good photos of your work on card stock at a minimum. Include your booth number and contact info on the price list, the shows are typically multiple days and buyers will have to find you. Also include your payment terms (in 12 years of retail shows I only had one bounced check, galleries were much more often late in payments, or had the checks get "lost" in the mail).
Check out the shows before you signup for both retail and wholesale. Other peoples work needs to be a similar level of quality and to some extent price point. It is hard to sell $2,000 sculptures at a show populated with beer can birdhouses and tie-die tee shirts, not to mention imported goods being rebranded as hand crafted.
The last report I got from a fellow craftsman who was at a formerly good wholesale show in 2014 (ACC) was that both attendance and sales from buyers have plummeted. This was both from their experience and an informal survey of other folks doing the show.
Don't leave your booth unattended. Should be obvious, but I've seen it happen dozens of times.
Selling is tough. Try to get someone else to do it with, or for, you if you are not good with people (fortunately my wife was excellent).
It can be very difficult to break into wholesaling, as some craft galleries are reluctant to buy from someone that they haven't already had a track record with, or have seen at the shows for years. My first year selling wholesale was quite an education in patience. Be prepared to sit for a couple of days at a show, with a smile on your face and few, if any, sales to attract that last minute shopper. Most buyers will go to their regular suppliers first, both to see what is newly offered and to get into their production schedule. As a new wholesaler you are far down on the totem pole.
Good Luck