Here's one I made Earlier

Check Book Holder
Materials: Used USPS Tyvek Envelope, thin transparent plastic, thread, tape,
Tools: Sewing machine, scissors, cutting knife,
Check book holders are functional but don't ooze individuality so I decided to make my own version. I had a disastrous first go using fabric as I didn't measure properly and ended up making it too small. It's pretty quick to make, use your original check book holder as your template and make yours at least a cm bigger so when you sew it you don't make it too small for the check book. Use two sheets of tyvek to make it stronger, optionally you can use cardboard to make it stiffer. Sew both sheets together. Use tape to hold your plastic inserts in place and sew around three edges leaving a gap for check book to go in. Repeat on the opposite side. Et voila.