I would say any block with lots of bias edges to match up. Those are tricky little buggers.

My most difficult/complicated block was this feathered star. It's wonky, and lacks 'perfect' points - but it was a fun learning process and its the center of a much larger UFO project. =)
Paper Piecing is another personal challenge for me. Nope - don't like it & avoid it. =)
Donna Mc

https://scontent-atl3-2.xx.fbcdn.net...qg&oe=65A55FA9

Mine was the twisted log cabin.

Sandybeach, that block is right up my alley! Love it. I'm gonna Google it!

This one with lots of different baskets was challenging.


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Hollow Star
 

Definitely sewing this quilt with diamond shaped pieces. The whole quilt was Y-seams. A real nightmare...never again!

Card Tricks for me too! Once I mastered that, the rest seemed easy...with a little patience!

Hey look at that, a moldy thread that is actually fun to go back to read and post updates! 😆

Mine was a Judy Martin log cabin variation that I made with much love for my MIL in 2009. Each block had 76 pieces in it, I made it king-sized, 11 blocks by 11 blocks. That's 9196 patches, if you're counting.

Sad story - I recently found out my MIL has given every quilt I've ever made for her away to people I don't know. The last time my husband and I visited, this log cabin was no longer on her bed. My husband poked around everywhere looking for it - he looked in closets, under beds, in boxes, in storage, etc. It's gone. I told him it doesn't matter anymore, I don't care if it's gone. I wouldn't want it back because just looking at it would remind me of how hurt I was.

For those of you who will chide me for being upset about it and tell me that once a quilt is gifted, the owner can do what he/she likes with it - this is true. BUT. She gets me to make these beautiful quilts for her (yes, she has specifically asked me to make quilts for her, picked out the pattern, fabric, etc) then enjoys getting all the kudos and admiration from people when she gifts the finished product to them. The time and love I put into HER quilts do not matter to her at all; what she likes is the attention SHE gets when she gives my work product away. Burns me up. And no, I will not make any more quilts for her and I told her that to her face.