Made a start on my idler today, found an old axle off a mower deck and a pulley, a couple of bits of tube and a piece of flat bar also from a deck,
ive drilled the 3/4" rod and tapped a 3/8" thread in one end to hold the pulley and drilled a 3/4" hole in the flat bar and welded them together.
the tube will be welded on to hold it central in the attach a matic hitch once i get a belt to align it up.
once i get a belt i can weld the bar for the tension spring and fit the other pulley.
heres some photos