Certain types of manhole covers and grates have a slotted hole in them designed to accept a T-shaped lifting tool, commonly referred to as a manhole key. Such lids are rare in Alberta and the Midwest USA, but they are abundant in other places, most notably in Australia.
A drain key can be made from welded bar or by cutting the profile out of the appropriately sized flat barstock.
You can weld one up simply from mild steel or take a 20mmx8mm aluminium bar and cut it to the appropriate shape. It looks like this:
+-------------+ | +---------+ | | | | | | | | | | +---------+ | <-- handle (for hands, straps etc) +-----+ +-----+ | | | | | | <-- less than 12mm diameter | | +--+ +--+ <-- the end you stick in the manhole cover slot. +-------+ 8mm high, 5mm thick steel
<- 25mm-> (or a little less)
To use: Stick the T end in the slot on the cover, rotate 90ø and pull up. These are the dimensions for Sydney's Durham covers. In SA and VIC different sizes are used but all operate on the T principle.