You are presented with six chocolate Easter eggs of which you are to choose three.

Problem

You are presented with six chocolate Easter eggs of which you are to
choose three.  Two eggs have been wrapped in red paper, two in blue
paper, and the remaining two in green paper.  Exactly one egg of each
pair has a hollow core but you can't tell which one it is from outward
appearances, but it does make that egg slightly lighter than its
similarly wrapped counterpart confectionery.  All three hollow eggs
weigh the same, as do all the three solid eggs.  Naturally you want to
end up with the three solid chocolate ones.

You are given balance-type scales with which you can compare weights of
contents placed on either side of the balance -- whether they balance,
and if they don't, which side is heavier.  Unfortunately the scales are
demoware from an aggressive weighing-ware company and they're designed
to only work twice before the mechanism completely fuses and you're
forced to register them for a fee.

How can you sort out the solid eggs from the hollow eggs?

E.g. if you weigh one red egg against the other in the first weighing,
then do the same with the green eggs on the second weighing, you now
have no more weighings to find out anything about the blue eggs.

But with the correct combination of eggs on either side of the scales in
each of the two weighings, you can sort the solids from the hollows.

-- Ziffer Mavis <z.mavis@warpcore.co.uk>