I recently made some simple business cards to hand out. Since most of my designs include a handmade element, I wanted my cards to as well.
Doily envelopes are easier to make than you may think! The original tutorial I used can be found here, but I improvised a little since I could only find round doilies at the store.
The basic idea is to make a template of your envelope shape, trace it on to a piece of vellum paper and cut out. Use spray adhesive to adhere a doily to your vellum and cut to fit. Fold and secure the inside of your envelope with double stick tape. Pretty easy, right? I think they would be great for a wedding invitation.