Cake Sculpting with Rice Treats and PVC

How to Sculpt Cakes Elements with PVC and Rice Treats

This tutorial demonstrates how to sculpt 3D cake elements out of PVC pipe, rice treats, and modeling chocolate.

This cactus, jalapeño pepper, sleeping Mexican cake was 100% the vision of a a client. The cakes are all finished in modeling chocolate. The sombrero is made of gumpaste and the interior of the standing cactus is made from PVC pipe and rice treats. This post demonstrates how the 3D cactus was engineered.

PVC elements used in the standing cactus


A PVC pipe cutter is a good gadget for trimming pipe and is also ideal for cutting plastic cake columns. For this shape, use 3/4″ (19 mm) diameter PVC and various joints and caps to achieve the cactus shape. It is critical to first cut and lay out all the intended pieces as once they are slipped together, it’s hard to take them apart.

For anything standing, opt for a wide base to absorb the shifty weight of the structure. The wider the platform, the less likely it is to fall over. A 20″ (51 cm) corrugated gold drum is used in this case. Trace the other elements, arranging them so that their net weight is evenly distributed. Screw the plug fitted for the base of the cactus into the drum.

Because the cactus is heavy and apt to rip the screw through the corrugate, secure the back side with one or two thin pieces of wood. Install a wooden frame underneath. The frame serves three purposes. 1) To create a cavity for the slats to nest in 2) To fortify the base 3) To create a lip around the edge that will make it easy to lift and place the cake down for transport. Electrical tape is handy for holding the wood in place while screwing in the ends. Secure the screws down through the drum and into the wood frame.

The cactus, which is one and half feet high, requires two batches worth of rice treats. For the rice treats, omit the butter that is listed in the standard recipe. This will make them less greasy and more sticky, which will help them adhere to the PVC.  To maximize stickiness, omit one cup of rice cereal per recipe. Do not press the treats into a pan as per the usual method. Rather, store them loosely in an oiled and covered bowl.

Roll out chunks between two pieces of wax paper to create sheets. Use these to wrap around the pipes.

Brush a thin layer of corn syrup onto the PVC piping before adding the treats. This will act as a natural glue.

Squeeze sheets of treats around the outermost arms. If a part is not adhering well, wrap a sheet of wax paper around the area and roll a small rolling pin over it to help the treats bond into one solid shape.

Cover the rice treat shape in thick sheets of modeling chocolate (or fondant). Because the treats are sticky and contoured, the modeling chocolate should adhere like velcro.

Secure the cactus to the base knob and begin decorating. With a knitting needle or pointed stick, add ribs and texture.

Pipe on the white chocolate prickers. View my video on how to make parchment paper piping cones.

Bolster the base of the cactus with a mound of rice treats for added support. Brush with white chocolate and cover with cake crumb “sand.”

Use plunger cutters to cut blossom flowers out of modeling chocolate. Place them at the tips and in the crux of the cactus arms to create a flowering cactus effect. Brush the cactus with gold and yellow luster dust and a little cocoa powder for a dry desert look.

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Cake Sculpting with Rice Treats and PVC — 16 Comments

  1. Great tutorial, I can’t wait to try making my first structure..I also just bought your book and I’m super excited about it.

  2. Thank you for those VERY helpful tips – one more question: how do you make the RKT smooth enough to cover it with fondant without the rice shape showing through?

    • It helps to use a fondant smoother or rolling pin to go over the rice treats so that they get as flat and compressed as possible. There will still be pockets and bumps though so after that, covering the rice treats with a thicker layer of fondant or modeling chocolate will help prevent the contours from showing through.

  3. Hi Kristen! I just got your book and it is over the moon! Wow! So much education and information! Thank you so much!

  4. Your work is absolutely mind-boggling. To Claire, who said. “Wow, just…wow!,” I can only say, “Amen.”