Making Your Own A9 or Half Fold Envelope with Triangular Flap

Purchasing envelopes today is either very expensive or the only ones available in A9 size are made from kraft paper as open-ended rectangles, which was not the look I wanted for these large envelopes. I wanted the “Baronial” style which has triangular flaps and will show a pretty lining paper.

The template is large for this size, so it’s not generally available online because it doesn’t print on letter-sized paper. You can buy plastic templates for envelope making but I didn’t want to spend the money. Anyone can make these, there is no need to buy envelopes from other people or buy expensive templates.

I drew my own template up to fit on a piece of 12 x 12 inch scrapbooking paper when placed diagonally on the sheet. I used a large sheet of plain newsprint to draw the template and then glued it to Bristol board and cut it out so I could trace and cut multiple envelopes.


To begin, rather than endless measuring, cut out a separate 5.75 x 8.75 inch rectangle from Bristol board, which is the finished size. Then measure off the midpoints on each side of this rectangle and draw horizontal and vertical lines across this template. (Shown in red below.)

I used a square Omnigrid plastic ruler to draw up an 11.5 inch square on the newsprint. If you use a regular ruler to draw this, make sure your drawing is completely square with no wonky lines. Then lightly place diagonal lines from corner to corner each way. (Shown in blue below.) Then place the rectangular template in the middle, matching the lines on the rectangle to the diagonal lines on the 11.5 inch square which ensures that everything is centred. Trace around the rectangle and remove it.

(Note: I forgot to take a picture at this stage so I took a picture after I’d drawn the flaps and notches in case you’re confused.)


The next thing is to mark the notches for the corners. Use your square ruler (or the corner of a piece of cardstock, anything with right angles), and draw a triangle there, then measure out a bit on each side, about 1/8th of an inch. Then draw a new line from the tip to the new marking. This extra room will allow the envelope to fold nicely without paper bunching up in the corners.


Then take a 1-inch circle or a small coin and round the top flap out nicely. For the bottom flap, measure in 2 inches on either side and draw a line across the marks, then cut that point off. The template will look like this.


Glue that to Bristol board with a glue stick and trim it along the outside lines just inside the marked line, then cut out the notches. The template is now ready for tracing on scrapbooking paper. I worked up a small prototype to make sure it all worked.


To fold the flaps I used a thin plastic ruler laid edge to edge and bent the paper over it, then smoothed it down with a bone folder for crisp folds. Use a glue stick to glue the side and bottom flaps together with the bottom flap folded over the sides.




I weighted mine for a few hours to make sure the glue stuck and to make the folds crisper. If you cut multiple envelopes at a time, weight them all together under heavy books, you don’t have to weight them separately.

For the second piece of paper to use as a liner, trace the 5.75 x 8.75 template again on newsprint and then trace the rounded top flap from the envelope template on top of one long side of that rectangle. Cut off 1/8 inch on the right and left sides of the rectangle shape. Measure 1/2 inch in from the edge of the flap on EACH side and draw lines and use the circle again to round the top; trim that down. Glue to Bristol board to get your finished liner template.

Here is a liner cut with this template. Remember, you are a human, not a die-cutting machine, small imperfections are unavoidable.


Slip your liner inside the envelope, centre it, and crease the liner on the same line as the top flap of the envelope. It’s important to crease it BEFORE gluing.


Then turn the liner flap back gently, apply glue from a glue stick, and press it back to anchor it to the envelope flap. You don’t need to glue it in below the flap.


At this point you can open the envelope and weight the flap for a couple of hours to ensure that the flaps stick together.

And these are the finished envelopes, back and front.



I bought some 4 x 2 inch permanent self-stick labels at the dollar store and want to draw some coordinating motifs on the labels. To get a return address label I cut the mailing label in half along the long side, and cut it down the side by 3/4 inch so it wouldn’t be too long, and will draw another small coordinating motif on it to match the big label.

I figured that I’d gone to all the trouble of buying paper and making these, so I wanted them to look coordinated by having a fancier label. This is a sample of the one I did for my prototype envelope with coloured pencils. I tried to emulate the main motif and/or the lining paper in colour and style.


I haven’t bought stickers for years but I bought two small packets to use on the back of the envelopes when mailing them.


You can use this same approach to make an envelope for any card. Some of us like to make cards from odd sizes of watercolour paper or other art paper, so it’s easy enough to use the card size plus some wiggle room (about 1/8 inch all around) and draw up a template similar to this, and then make a custom envelope for your art card.

I’m all set for writing letters with my fountain pens and putting them in bespoke envelopes.




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6 Responses to Making Your Own A9 or Half Fold Envelope with Triangular Flap

  1. What lovely envelopes, thanks for sharing. Karen

  2. mooninfog says:

    Very nice, Judy–I admire your aesthetic sense AND your patience!

    • JJ ColourArt says:

      Thanks Debra. I’ve always liked fiddling with paper. I liked this so much that I made a smaller template and made another 8 lined envelopes. By that time even I was losing patience.

  3. tarottiferet says:

    Those envelopes look fantastic!!!

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