3DC in each hole, then single crochet to get the shape you want. Felt for the sole should do.
Diy shadow box from a shoe box. Use for seasonal items that you want to switch out and don't need to be in a fancy box.
Style, Decor & More: DIY Pillow Cover Tutorial
Salvage ripped flip-flops by making a more comfortable version. (or tear them apart from the start because this is way cuter)
Cheap Screen Printing (the easy way)