Cake postcard tutorial

cake postcards

Make a mailable slice of cake

I have so many friends and family members that always say "I wish you could mail me a birthday cake!" ... well, now I can send them a slice.

Imagine how happy and excited you'd be, if you went to your mailbox one day and pulled out a slice of cake. Now you can surprise friends and family (and probably even your mail carrier), with this three-dimensional, mailable postcard, cleverly disguised as cake. With only five ingredients in this crafty recipe — a large sponge, spray paint, caulk, spray adhesive and heavy paper — it's a piece of cake. Literally. Postage is around $3 per slice, but the reaction from the recipient will be priceless.


Materials needed to make two cake postcards:

  • 1 large sponge (yellow paints the best)
  • Serrated knife
  • X-Acto or utility knife
  • Spray paint (brown, yellow, pink or white)
  • 1 tube acrylic latex caulk (brown, cream or white)
  • Spray adhesive (3M Super 77 works great!)
  • Cardboard, kraft paper or scrapbook paper



Cut sponge into wedge shape

Postcard Cake Step 1: cut the sponge

With a serrated knife, using a sawing motion, cut a sponge into two, cake wedge shapes. Large sponges can be found at hardware stores and in the automotive departments of most big discount stores.


Cut a center groove into sponge

Postcard Cake Step 2: cut center of sponge

Using an X-Acto or utility knife, cut a section of foam from the center of the sponge. It doesn't have to be perfect. Just cut a wedge big enough so that you can add a line of caulking there later.


Paint the sponge

Postcard Cake Step 3: paint the sponge

Paint the sponge wedges in desired color. (Brown looks the most realistic, but pink and yellow are fun too. White was probably my least favorite.)


Trace the slice of cake

Postcard Cake Step 4: trace around the sponge
When the sponge wedges are dry, trace around them on a piece of cardboard, kraft paper or colorful scrapbook paper. This will be the postcard side of the cake. Heavier paper works better and will give you a sturdier wedge of cake for mailing. Cut the postcard shapes from the paper.


Attach the postcard

Postcard Cake Step 5: attach the postcard

Spray glue the postcards to the solid, flat sides of the sponge wedges.


Prep the "icing"

Postcard Cake Step 6: add caulk to piping bag

Using a caulking gun and your desired caulk, fill a plastic disposable piping bag with half of the caulk. This should be enough to do one cake wedge. I was able to pipe two cake postcards with one tube of caulk, but I recommend putting only half of the caulk in the bag at a time. Also, I tried decorating my cake wedges using the caulking gun, but it was nearly impossible to control. It's much easier with a piping bag.


Pipe the center of the cake

Postcard Cake Step 7: pipe the caulking

Pipe a line of caulk down the center of the cake postcard wedge, where you removed the sponge with your knife.


Pipe the icing on the top

Postcard Cake Step 8: pipe caulking on topPipe dollops and swirls of caulking on the top and sides of the sponge wedge just like you're decorating a cake. Pipe along the edge of the cake postcard to form a seal between it and the sponge.


Add the swirls

Postcard Cake Step 9: swirl with paintbrush
If needed, use a small paint brush or toothpick to swirl and adjust the thickness of the caulk on the cake top and side.

Allow your cake postcards to dry for three to five days. I placed mine on sheet of parchment paper and lifted them up periodically so that the caulk wouldn't dry and adhere to the paper.

Postcard Cake Step 9: let dry

Write your message on the postcard side, leaving enough room for an address and postage. Sizes, shapes and weight of each cake postcard will vary, but most of mine required three, $1 stamps.

Postcard Cake Step 9: back of cake postcard

Note from the editor

This totally works! I had Sandra mail me a slice of cake so I could see it with my own eyes. It made it to me in perfect condition. I could hardly believe it. See for yourself below:

Proof that you can in fact mail a slice of cake.

mailed cake postcard

Video how-to: Cake postcard

Not into diy?

Fear not! You can still have your cake and eat it, too. Check out this Etsy shop where you can purchase your very own mailable slice of cake.

Pumpkin pie postcard


Check out our
DIY pumpkin pie postcard tutorial

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Add some flair with a DIY painted wood bead necklace
Birth-daisy cupcake craft

Tags: postcards

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Comments on "Cake postcard tutorial"

starlett March 07, 2014 | 4:11 PM

lmaoo omggg i would be SOOOOO disappointed if i got this in the mail, they look delicious. and to find out its fake and i cant eat it. ---- lol.

Sandra February 13, 2014 | 6:24 AM

Thanks Carmen! I hope you enjoy making them as much as others will enjoy receiving them.

Carmen February 12, 2014 | 11:00 AM

This is wonderful! thanks for sharing the step by step process... It looks like people who lack creativity will always have negative things to say, but for those of us who love to be creative and productive, it sure is a wonderful project to work on this weekend! 10 stars :)

Maggie February 10, 2014 | 7:11 PM

Why on earth would anyone do this? Do people not have anything better to with their time?? I can't believe this is a real thing on the Internet.

Allana December 23, 2013 | 2:23 AM

Hey, for anyone who is wondering, if you cut an oval sponge and paint a swirl on it, it could be a chocolate yule log :)

Paula December 06, 2013 | 10:13 AM

Love it would like to makes some for friends. Will get the material and work on it this weekend

Nicky November 11, 2013 | 4:54 AM

Too pretty! Could you please publish a tutorial on how to do swiss roll slices (log cake for christmas!)??

Tammy Whitley November 06, 2013 | 1:06 PM

That is the coolest thing I have seen in a while. I totally love it and will be getting the supplies to give it a try this weekend!! Thank you so much for sharing such a great DIY project!!!! 5 Stars in my book!!!

Jason October 08, 2013 | 8:33 AM

I decided to make these as thank you cards and they came out great! I can't wait for them to reach their destination. One thing that other people might need to know is that my post office needed to put two large stickers on the post card side - including one for tracking even though I didn't get tracking. The post office worker says its required now. The stickers are larger than three stamps put together. September 29, 2013 | 12:29 PM

Wow, that is very very creative. Love the idea! Thanks :)

Rae September 28, 2013 | 10:57 PM

I had some light coffee-colored spray paint leftover from painting a fan. I thought it would work for the cake, but it's become more gray than light brown. The only other paint I have is solid black at home -- would this be too dark to pull off as chocolate? Have you tried it with black? I have a milk chocolate frosting, FYI. Thanks, and awesome idea! One person came to mind for this gift and her birthday is the first week of October, so I had to try it!

Judy September 27, 2013 | 1:04 PM

How creative!! Keep them coming.

Diane L. September 16, 2013 | 6:35 PM

Thank you for sharing this really great cake project. Have so many friends who will love finding this surprise in their mail box. One did you achieve the really dark chocolate brown icing? I used the same brown caulk as shown in your photo which turned out more of a "milk chocolate" look. Would appreciate knowing the brand name and color for the dark brown icing. Or maybe it is painted?

Sandra September 02, 2013 | 10:32 AM

I can't remember exactly the color/brand of paint I used, but I almost always buy Krylon. And I seem to find better color options at Home Depot. Mine was more of a buttercup yellow instead of lemon or sunshine.

Amanda August 24, 2013 | 6:40 PM

what color/brand of spray paint did you use? I bought a dark brown that worked great but my yellow looks so bright and unrealistic. Does anyone have tips for which shade looks best?

Lilly August 22, 2013 | 2:07 PM

There's some major butthurt going on from people that have nothing to do with all of this. DIY is Do it Yourself and if you*re crafty you're gonna do it and if you're lazy and have a couple of bucks to spare you're gonna buy it. The End.

Christina August 18, 2013 | 6:04 AM

This is absolutely adorable and look so genuine! I can't wait for an excuse to make one- but they I guess they would be cute just displayed in the kitchen!

Sandra August 16, 2013 | 7:27 PM

Why spray glue? Well, it goes on nice & flat, it's super strong and it dries quickly. It won't bubble or leave wrinkles like paste glue. I'm sure any number of glues would work just fine. (I'm a graphic designer, so spray glue is my #1 choice almost every time.)

Sandra August 16, 2013 | 7:23 PM

The pink frosted slice is one that I painted. You can paint any of the caulks whatever color you'd like after they dry. Just be sure the tube of caulking you buy says "paintable."

Jenna August 07, 2013 | 5:28 PM

Why spray glue?

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