Express Post (Quilt) Block Party Week 4: How to Make an Open Envelope Block

MAR 26, 2021 updated Jun 5, 2021
Boy holding up a finished open envelope quilt block

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Continuing our “block party” in celebration of National Quilt Month, artist, designer, quilt maker and Spoonflower Ambassador Andrea Tsang Jackson of 3rd Story Workshop will be showing you how to make an open envelope quilt block from her Express Quilt. This beginner-friendly quilt project is made with Spoonflower’s Cotton Poplin and Fill-A-Yard®, but any of our quilting-weight cotton fabrics will work great. This is the last of our four-part “block party”— thanks for joining! Now you’ll have all the steps to make your own mini-wall hanging or pillow.

Express Post (Quilt) Block Party Schedule

March 5: Choosing Designs 

March 12: How to Make a Closed Envelope Block

March 19: How to Make a Heart Block

March 26: How to Make an Open Envelope Block

Graphic introducing the open envelope quilt block

Andrea: This open envelope block uses a technique common to the traditional “economy block. ” Try fussy cutting your envelope “liner” fabric for a fun way to feature your favorite fabric motifs. You can use scraps or the recommended fabric requirements for the whole #ExpressPostBlockParty project.

How to Make a Open Envelope Quilt Block

Step 1. Prep Your Open Envelope Fabric

Main envelope:

  • (1x) 3.5″ (9 cm) square, cut corner-to-corner to make (2) triangles
  • (1x) 1.5″ x 5.5″ (4 x 14 cm) rectangle

Envelope “liner” fabric:

  • (1x) 4″ (10.5 cm) square (try fussy cutting to feature a favorite fabric motif!)

Background fabric:

  • (1x) 3.5″ (9 cm) square, cut corner-to-corner to make (2) triangles
  • (2x) 2.5″ x 6.5″ (6.5 x 16.5 cm) rectangles
  • (2x) 2″ x 9.5″ (5 x 24 cm) rectangles
Fabric laid out to make block

Fabric for one open envelope block

Step 2. Make The Open Envelope Quilt Block

To mark the center of the long side the triangles, fold the triangles in half as shown. Similarly, fold the envelope “liner” square in half in both directions to find the center of each edge.

Take one triangle of each fabric and center the long sides on opposite edges of the square.

Join with a scant 1/4″ (2/3 cm) seam allowance. Press seams toward the triangles and trim overhanging fabric.

Repeat with the other two triangles. Press seams toward the triangles.

Square up the block to 5.5″ x 5.5″ (14 x 14 cm). Line up the 2.75″ (7 cm) line with the center points of the block and trim each side. This is how you start to make a traditional economy block or square-in-a-square block!

With a scant 1/4″ (2/3 cm) seam allowance, join the 1.5″ x 5.5″ (4 x 14 cm) rectangle of main envelope fabric to the bottom of the envelope. There’s your open envelope!

Step 3. Make The Background

Add the side borders: Join the 2.5″ x 6.5″ (6.5 x 16.5 cm) background rectangles to the right and left of the envelopes with a scant 1/4″ (2/3 cm) seam allowance. Press the seam allowance away from the envelopes.

Add the top and bottom borders: Join the 2″ x 9.5″ (5 x 24 cm) background rectangles to the top and bottom of the envelope block, with a scant 1/4″ (2/3 cm) seam allowance. Press the seam allowance away from the envelope.

Finished open envelope quilt block

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To finish, join the heart block and open envelope as shown in the diagram below. Then add the closed envelopes to the left. You can then quilt and bind it to make a wall-hanging, or transform it into a throw pillow!

Diagram of how to sew all blocks together
Finished quilt blocks, pre quilted and binded
Finished Express Post mini wall hanging on brick wall
Finished Express Post pillow on bed

Looking for a fun space to connect with other quilters?

Thanks so much for joining us for the Express Post Block Party! Don’t forget to share your progress in our Facebook Group, and tag your posts with #ExpressPostBlockParty and #SpoonflowerQuilts. You can find Andrea online at 3rd Story Workshop (where you can find the full Express Post quilt pattern) or @3rdstoryworkshop on Instagram.


Headshot of Andrea

Meet Andrea

Andrea Tsang Jackson of 3rd Story Workshop is a textile artist, quilt designer, author and educator. After working in various design fields and settings ranging from architecture to museums, the quilting medium called to her as a way to explore place, belonging and agency. Andrea lives in Halifax, Nova Scotia, Canada with her husband and two sons.

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    I love these!!!! So beautiful! Reminds of my dad, a mailman, for 30 years and my mom a quilter for 60 years! Thank you for sharing!