The light-table is the size of a small table in my case, because it was a hand-me-down from my old employer. You can buy portable desk-top light boxes from art stores.
Before I had the light-table I would use the window! Seriously. I'd tape the sketch to the glass, then tape the paper to the glass and use the outside light. The only problem with this method was my arm sometimes got a bit tired working 'up', and I was restricted on the hours of the day that I could do it. Couldn't do it at night! ;~P

The figures in this painting were mostly coloured with markers.

Questions are not a problem. :~) That was the purpose of this.