Step 1) Make a 12.5" quilt block using only solid fabrics. Choose solid fabrics in colors you love, 12" finished size - that is all you need to remember for April.
Step 2) Put your block in a paper bag with your name and email address. Swap it at the April meeting and meet up with your swap partners before you leave.
Step 3, the challenge) Turn that block into _______ and return it to it's original creator at the May meeting. Into what? The challenge portion will be announced at April's meeting.
Step 4) Give the challenge item back to it's original block creator at the May meeting.
Yes, you get your block back as a completed project.
Some solid inspiration can be found on The Modern Quilt Guild's Robert Kaufman Kona Solids Challenge Quilts flickr group.