There are some nice set pics in the March issue of Trapper and Predator caller mag, too.
the one with the two sections of what look like "telephone poles" blocking down the opening approach to the castor mound is a great pic. The opening between the two pole ends is just large enough for the #330, and shows the stabilization sticks used, too.
This pic of course also shows that #330 with a nice beaver in it already, but also demonstrates that there wasn't much of a struggle after the catch either as the set is relatively undesturbed. The trapper also did a nice job of making that #330 set back far enough from the castor mound on the bank that the set will be a snap to remake. The critter never even got close to the mound, so no maintenance needed at the mound...only to remove the dead beaver and reset and stabilize the trap.
This same set could be modified using just about anything around nearby to fence down the approach to the castor mound as this trapper did with the two poles.
I thought for someone wanting to try #330s at castor mounds, this issue has some pics that say a 1000 words for teaching set construction and trap placement.
Jim-NE