Here are the pieces in three 6x10 rectangles. It's rather simple to get
six 6x5 rectangles, if you start with the three 6x5 rectangles for the
unchequered onesided pentominoes and add two different chequerings.
With the 36 pieces you can make sixfold replicas of each pentomino as shown
for the C in the title.
Andrew Clarke has all other solutions on his site.
A strip with width 3 and length 60 can be derived from
a construction with the unchequered pieces. Here are some rings of similar width, where
the edges have an odd number of squares. In this case you can't easily double a
construction with the simple pieces.