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Wow, that's a very good start for a beginner! There's a lot of buttons and knobs there, but I'm not sure about "lighted" buttons. Do you mean like at the top, beside the button labeled "SELECT", where it says "INTENS" with a tiny light beside it (which I guess indicates it's activated)? If that's what you mean, I'm not sure I would change it. I do see how the light radiates outside the border, but that's what I'd expect. Although maybe a little more transparency would reduce the brightness. Or maybe that's not the "lighted" button?
But just in case you want to eliminate it, there is a way to do it, using Clipping. First you'll need to duplicate the path. (You may want to give it some outrageous color. When you perform the clip, the path will seem to disappear. So theoretically it shouldn't matter what color it is. However, if you're working in a situation like this (which often occurs in realistic drawings) you may have several stacked up objects to effect shading/lighting. If you ever need to release the clip later on, for some reason, that clipping path will reappear. If it's the same color as the original, it might be hard to know which objects are which. So if it's some outrageous color, you'll know it's the clipping path.) Select that new path and the original, then do Object menu > Clip > Set.
One area that stands out to me is the knobs/dials. Well, not that I'm very familiar with this machine, but I do have an old stereo that's made with this metalic style. Anyway, the knobs look too light/bright to me. I do think they need to be a tiny bit lighter, to enhance the 3D effect. But maybe not that light? Also...hmm...it's hard to say. It looks like they aren't casting any shadows. Or maybe there's a shadow, but they're too light?
Another thought on the shadows. Using the thing labeled CH2, there seems to be a gap between the shadow and the....I don't know what to call it, it looks like something gets plugged into it. Anyway, the shadow should extend to the base of that thing, rather than start at the edge of it. I know that when you drew it, it probably matched the edge perfectly. But when you add the blur, it causes the apparent gap. In order to get rid of the gap, you need to drag the nodes of the shadow until they are well behind the thing (plug). I could work up a quick illustration, if you don't understand what I mean.
On the handle, I think it's something to do with the lighting and shading, that make it look not realistic. But there's something funky with the lighting, in the image as a whole. On the right half of the face of the machine, the shadows seems to be cast down and to the left, so that the light appears to be coming from top right. But the buttons just to the right of the screen on the left half of face of the machine, seem to cast a shadow to the right and down (indicating light from top left). And on the handle, the light seems to be coming from top left. So once you have the lighting and shading consistent in the whole image, I think the handle will look better.
And one last couple of things that jump out at me. Where the handle connects to the side of the machine, it seems to me the handle should cast a shadow on the side of the machine. And there's a panel of buttons labeled "TRIGGER", where the word trigger seems to have slid off the panel (or maybe onto it).
I agree about the bevel around the screen. I don't know what to suggest, since I'm not familiar with the machine. But you must be working with a photo, or maybe the actual machine?
Very nice work on the whole of it! I can't wait to see how it progresses
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