.....after looking into purchasing a slatmill I found only three options which were The Dog Trotter, RP Millmaker, and Ghostrider. In respect to the hardwork & craftsmanship these guys put in there stuff I'd like to start off by saying all three are very good mills. Now personally, I won't buy any of them.
Starting with the Trotter, the gambler has crossed into a new market to sell his mills to, because of that his prices are simply too high for a working dogman. The new design is cool but unnecessary. Those plastic slats bow in the middle, you don't need a damn speedometer,due to laziness he switched to the aluminum frame which is is too light for my taste, he even gives slightly off specs over the phone in fear of a copycat. "Uh hello dipshit if I really wanted to copy you that bad I can simply buy the damn thing and reverse engineer it, you sell the plan every time you sell the mill genius.
On to the RP Millmaker, only three things keep me from this purchase, first of all the slats are too skinny and not beveled, second thing is some people receive them brand new but damaged from shipping, which brings up my last point, he's too far away to go through all that shit.
Ghostrider mills are solid but the guy is too lazy to take that extra step and put a bar on it for chain hook up, & his logistics are somewhat of a mystery to him! (Smh) quality comes first.
Now look at my argument, when walking or running a dog outdoors how many of you have a damn speedometer, heart rate monitor, or a fucking brake handy??? Bells and whistles only mean repairs to me. If you are fully focused on your dog and know how to work it on a good solid basic mill all you need is dedication and hard work. I guarantee the dog don't know how much you paid for it, don't care how many mph he runs. Basically His body language, pads, breathing, and the look in his eyes will tell you what you need to know.
If you could take gamblers willingness to research how to upgrade, ghost riders fair price, and RP's dedication to purpose you can have exactly what YOU want a fraction of the price and hassle.

I am currently building my own mill with the help of a welder for my steel frame, a cnc fabricator for my return wheels and track railing, a woodworker for my slats, and a powder coater incase I decide not to candy paint it. Carefully making sure everything was level I'm starting with a good and simple frame, after I get my parts from the fabricator I'll bolt it all on and if need be make the necessary adjustments to ensure proper function, after that's out the way then I will finish it off with some style all the while keeping it basic and free turning. If a fail, which I doubt will happen, then hey I tried. If I pull it off, then I will have saved a ton of money, learned something new and give my dogs a solid safe piece of equipment to use! I understand it's not a piece of cake but it ain't rocket science either!
PS. The Curious mill was my fav one of all but he's not around so....