Hello RX7850
I have been modelling for the past 40 years. I own a both a 3.5 x Gallilean and a 6x prismatic loupe like the one in your pic, I don't recommend it for modeling as its very hard to adjust both sides to give you a centered image and also 6x is just to high a magnification since the field of view is so narrow, you get disoriented, loose your subject fro view and the focal distance is way too long, you actually have to lean back...they are made for people who work standing up with the patient at the height of their belly button.- Not recommended
My tool of choice is the Optivisor, by Donegan Optical, 2.5x... 3.0x at most...any higher than that and the focal distance is too short. Your x-acto or paint brush will be hitting it all the time.
2.x5 is the most useful in terms of magnification level vs focal distance. You'll love em'
2,5 may not look like much but its actually fabulous for model building...and I machine micro-miniature parts (down to 0.007in. wide) with them . I wear them all the time and wouldn't trade them for anything...