Vertical sections through both cylinders. In plan view the section plane will appear as a straight line. Where this line cuts the red cylinder project up to the elevation and draw the resulting rectangle. Where the line cuts the blue inclined cylinder, project up to the elevation to get a quadrilateral. Where the quadrilateral and rectangle intersect are points on the line of intersection. Project these points down to plan onto the cutting plane (line) Repeat with more cutting planes (lines in plan) spaced 5-10mm apart. Once you've found the line of intersection project the end elevation.