Go to Design and enter the desired width and height of your envelope.
Experiment with values of topFlap , sideFlap and bottomFlap to ensure that all the flaps overlap and to get the desired look
Then go to Cut and confirm that the unfolded envelope fits inside your Paper Size. Paper size is 8.5" x 11" by default but you can change those dimensions by selecting Paper Size and changing the scale. This reference shape won’t be exported.
Finally go to File > Export SVG to download the file
The first 5 minutes of this video also show how to do it.
For a quicker workflow you could also select the shape in the editor and copy with COMMAND/CTRL - C and paste into the Glowforge Interface, there you need to use the Edit menu and select Paste.
If stumbled upon this post looking for an a quick envelope fix here are a few SVG’s with common sizes.
The #10 envelope (4-1/8 x 9-1/2 inches) is the usual size for business and bills in the US:
The A2 (4-3/8 x 5 3/4 inches) envelope is good for invitations and note cards:
This 8-1/2 x 5-1/5 inches envelope fits an oversized postcard:
There are some really nice threads on the forum about cutting and scoring paper on the Glowforge: this post has a comprehensive list of settings for paper and cardstock. Holding down your material can be accomplished with a DIY method (spray adhesive on wood or cardboard), some people use magnets and some really like the Seklema mat.
I’ve mostly used the spray adhesive on cardboard method and it feels sufficient to me, though I’m growing curious about the Seklema. One nice thing about making my own with spray adhesive is that the stickiness is somewhat controllable, after spraying the surface I can pat it with some fabric until it’s just right.