Boiler, group head, steam pipe and fittings of brass, piping up to the boiler is nylon/plastic. Electrical components and wiring have a commercial grade look. Interior chassis is heavy guage steel. Exterior is light guage steel and plastic, and it flexes when attaching the portafilter - but the interior doesn‘t flex.
The portafilter is heavy chrome plated brass, the baskets are steel. Conclusion - the opposite of showy, the mostly invisible working parts are massively built and expensive, the mostly visible style parts are somewhat flimsy and cheap.
Operation - General
This isn't a super-auto, so getting the best tasting shot involves some time and effort. Turn on the machine and the steam switch. While waiting for the steam ready light, grind, load and tamp your shot into a filter basket, leave the portafilter attached to the group head
Operation - Steaming
There are no special steaming gadgets; but this is simply the best frother for home use, since there is an adjustable knob to match the steam flow with the amount of milk you‘re steaming. If you‘re making macchiatos, the steam is dry enough so the milk can be reused several times. First flush out the water from the steam line into a spare cup. The most basic foaming rule is to always keep the wand deep enough so you're not blowing bubbles, but not much deeper than that. This requires moving the frother tip deeper below the surface as the foam builds up. For a stiff foam with the consistency of beaten egg whites, froth so the milk stays calm; for a pourable "latte-art" foam like a Hollandaise sauce, froth so the milk swirls. After the swirly frothing, the foam and milk may separate while you‘re pulling your shot; they can be recombined with a folding motion.
Operation - Switching from Steam to Water and Preheating
Turn off the foaming switch, quickly flush the steam wand, then run the water through the group head and attached portafilter into your cup. The steam ready light will be on at first, then go off. At that point the machine is ready and the components preheated. If you have the patience, you can continue running the pump until the pump ready light goes off, then brew when it comes back on again. This gives a marginally improved shot.
Operation - Espresso making
For the very best in espresso, use the non-restrictor baskets (available as a $12 accessory at some sites, incl. sweet maria‘s and whole latte love) with freshly ground coffee and a heavy, 30lb plus, tamp. Keep an eye on the espresso streams as they enter the cup, when the crema there goes from brown-red to cinnamon-tan, end your shot. The restrictor basket requires a coarser grind and a softer tamp, so the flavor is less developed and the crema, lighter colored. However, with preground, older, or low quality coffee, the restrictor basket will usually give a better tasting brew, since it tends to block out the bitter and oily tastes. (If you use the restrictor basket, flush it out under pressure by pumping water through after every use since that's the only way to get the coffee oils out from between the double wall -- if you don't, it'll make your shots more rather than less bitter.)
Before I had access to good grinders and fresh coffee, I used various inexpensive "throwaway" machines (de Longhi, Briel, Krups, Capresso), since under those conditions, they didn't do any worse than the more expensive Saecos or Gaggias I also owned at various points. In the past few years, with micro or home roasted coffee and good home grinders available, the story has changed -- there are very tasteable quality differences among home machines.
Under these conditions, I think the Solis SL-70 is the least expensive machine that will give you an espresso equal to that found at the very best coffee shops. Without taking all these pains, the brew will be no better than a super-automatic‘s, for a lot more trouble and not much less cash, when you figure in the grinder. So if you‘re looking to invest some time in espresso making, this machine (with a non-restrictor basket and any of the excellent Solis grinders) is a good budget choice ($440) when compared to the Gaggia Classic/MDF ($600) or Rancilio Sylvia/Rocky ($625); since Solis does it‘s cost cutting in the cosmetics, while keeping the working parts at the highest quality.