Something slightly off about vehicle mode (the cab is too close to the trailer for one thing) but robot mode is one of the best so far in my opinion.
Face needs a little bit of work but it's still a good bot mode.
Next thing will be does he combine and what do the other Stunticons by this company look like (if there are any).
Good bot-size by the looks. Judging by his feet, though, the cab in vehicle mode will be a bit smaller than MP10. Can't have everything I guess, as MP10's bot is just the cab and Motormaster is the cab + trailer.
Bot mode is a good G1 likeness, Truck mode is pretty terrible, at that size will likely be half the size of Optimus.
this company I think it called Perfect Fusion, don't know how long they have been operating. They are currently releasing PF-01 not Slag atm.
Nah Perfect Fusion is a Fans Toys subline imprint, 01 is basically just Fans Toys Scoria with some updates to make it a "perfect fusion" of their designs etc.
Apparently this Motormaster is by a new company (though it's probably just an offshoot of someone we know anyway) called "Rising Force".
This Motormaster is RF-01 Magma and it seems that it's taken two years to get to this point in the design process if this thread I found on TFW is anything to go by.