The 'purest' way to produce the EoT mechanically is with 2 cams, the output of which are added together. One cam turning once a year simulates the Eccentricity Effect. The other turning twice a year simulates the Obliquity Effect. For astronomical clocks, designed to work in the longer term, this has the added advantage that the Eccentricity cam can be driven once per Anomalistic year (the time from one mean perihelion to the next = 365.259 636 days). While the Obliquity cam can be driven twice per Tropical year (the time from one mean vernal equinox to the next = 365.242 189 days)
The output from each cam is then added with a 'wiffletree' or other mechanism (as shown in the following video.
You can read a complete story of this unrealised dream below.... The description of the refraction correction is incorrect
Another double cam system can be found in Bill May's work. Here one cam sits inside another. This produces an effect similar to that of of two gears (see Gears page). The inner (circular) cam carries an eccentric pin that connects to the equatorial ring of a dial. The inner cam is carried eccentrically inside the outer ring. The inner cam is turned wide in the year (Obliquity effect) ; the outer ring once (Eccentricity effect)