So I select my page, trace the envelope template onto the page, cut and fold. I then use Elmer's All Purpose Glue Stick to hold it all together and to seal the flap when I am ready to mail.
I have been writing the mailing address on self stick labels and then covering with shipping tape, since I use fountain pen. I also have a return address stamp that I have been doing the same with.
This last envelope had some white space around the page that I used to write my return address and I did a final seal with my wax and personal seal.
Don't be afraid to try this, it really is simple and a lot of fun. I've had a lot of positive comments from the people to whom I have sent these.