Here's a couple of mine.
The big one is a lee 20# pro 20. The little one is the small 6 pound melter, but it does have a thermostat.
Here's a mold guide I made for the lee pro-20. The one supplied by lee couldn't be made to work by me. Not saying someone else couldn't get along with it.
Another view, I modified lee's guide by cutting the "ear" off and screwing the ΒΌ" oak strips to it. There's a chunk of 3/16 alum. angle used in there too. The guide allows the sprue plate openings to be accurately positioned directly under the stream of lead coming from the bottom of the pot. So you get this, a nice straight sprue puddle;
That's a lee 90342 mold, it casts a .429-250-SWC.