I have a custom bag to make this week but the buyer has requested it has a zipped main pocket, my brain has been itchy with thinking about how best to do it. Am quite confident that I could do it with a bag with a square top (good old youtube) but the bag design she likes has a curved edge that runs into the straps. I am thinking of doing the zip in a gusset (?) so you get a rectangle with a zip through the middle and attach it to the lining so that the outside look of the bag is not changed but the pocket would be more square once you are inside. Will have to try it out with some old sheets me thinks before I chop up the lovely fabric she has bought especially!
And because it is just plain rude to post without pics here is a little snap of the children doing an impromtu 'show' on a bench in the willow walk when we went to Wycoller;