SquidWeaselYay
Ski Diva Extraordinaire
That is really good advice, thank you! The duct tape foam already got torn up a bit from shoving it back into the shell.in the meantime, you can go to a cloth shop and buy a big fat roll of sticky-back Velcro. Cut strips any size and shape you want from the soft half of the Velcro, and stick onto the outside of your liners where you need filler. I've done this to the left and right edges of the ball-of-foot area of mine, and have even put second and third layers on top of each other. The sticky stuff is incredibly persistent in staying stuck. If your Velcro moves, cover it with duct tape. Your liners don't need to look good, they just need to be functional.
Serious creativity and resourcefulness points to you.