I've got a slide rule somewhere which does square roots. Multiply, divide, log, exp, squareroots, add, subtract. Plus I can draw a sliderule myself with litte or no aid. To draw that elliptic curve thingummy, I'd probably need a computer. --- So it seems to me, if you want to go beyond the sliderule, then you need to compute a function of THREE arguments. Suppose there were a curve on a 2D plane, labeled with numeric scales. Also in the plane is a 2D grid, labeled ditto. And you had a straightedge with a numeric scale on it and sliding T-square. You could intersect the straightedge with two given points on the curve, plus slide the T-square to intersect a third given point on the curve. Finally the point where the Tsquare and straightedge intersected, could be read off the grid. Hence you would be computing a function of three arguments. There might be other and better ways to do it. Question is, can we make something like this useful?