We are going to have a variety of blocks coming in. Two sets will fit in one envelope, if you do three sets, you will need to send two FRE for return and I will split the three sets into two envelopes. As far as I am concerned, all blocks are acceptable. There are 42 blocks promised at this point, and swap closes tomorrow (2/28). 3 sets will give you most of the blocks that come in. 4 sets will result in repeats of some blocks.