How to Cut Twisted Foam Body Strips for Fly Tying

A twisted foam body starts with a few narrow strips. Change their width, thickness, number, or colors, and you can create a very different fly: a slim caddis, a full-bodied hopper, or a stonefly with a more restrained profile.

That flexibility is the backbone of our Backcountry Halo Series. In the video below, we show how to cut consistent foam strips with a cutting board, straight edge, and rotary cutter. We also cover a quick way to size and cut foam for a bullet head.

Watch the fly tying tip: How to Cut Twisted Foam Body Strips

The idea behind the twist

We owe this approach to fly designer Robert Williamson and his Twisted Foam Hopper. Williamson was teaching his “Foam Twister” technique by the early 2000s, and his hopper showed what could happen when narrow strips of foam became an extended, segmented body. His work is the inspiration behind the twisted bodies we use in the Backcountry Halo Series.

The twist does more than make the fly look interesting. It gives the abdomen visible segmentation while letting us choose its shape and color mix. Foam adds buoyancy, and the extended body gives a larger insect profile without requiring that entire abdomen to sit on the hook shank. The result is a useful starting point for flies as different as caddis, hoppers, and stoneflies.

How to cut consistent foam strips

You’ll need a cutting board with measurement markings, a straight edge, and a sharp rotary cutter.

1. Lay the foam flat on the cutting board and line up one edge with a board marking.

2. Use the markings to set the width of your strip: 1 mm or 2 mm.

3. Hold the straight edge firmly against the foam.

4. Run the rotary cutter along the straight edge in one controlled pass.

5. Move to the next marking and repeat.

Using the board markings for each cut helps you produce strips of the same width. That consistency matters when you twist several strips together: each one contributes predictably to the finished body, making it easier to repeat a pattern across a whole batch of flies.

Choose the strips to shape the fly

A 1 mm × 2 mm strip gives you more foam per strip than a 1 mm × 1 mm strip. The number of strips then gives you another way to adjust body size. Color is part of the design, too: twisting colors together builds variation throughout the abdomen.

Here’s how we use those choices in three Backcountry Halo patterns:

Those recipes are a starting point. If a body looks too heavy for the insect you’re imitating, try narrower strips before giving up the color combination you like. If it needs more presence, add strips and see how the profile changes. A small change at the cutting board can alter the character of the finished fly.

Cut a bullet head to match the hook

The same tools make it easy to cut a foam strip for a bullet head. Place your hook against the cutting board markings and measure its gape. Use that measurement to set the width of the foam strip, then cut along the straight edge with your rotary cutter.

Foam thickness matters here as much as width. For larger flies, size 14 and larger, we use 2 mm foam to give the head enough presence. For size 16 and 18 flies, 1 mm foam creates a more delicate, proportionate head. Matching the foam to the hook keeps the head in balance with the rest of the pattern.

See where a few strips can take you

Robert Williamson’s twisted foam technique opened up a lot of room to experiment. That’s what keeps us coming back to it: with a handful of clean cuts, we can adjust the silhouette, segmentation, and colors to fit the insect we’re tying.

Watch the video, cut a few strips, and try twisting two combinations side by side. Which would you tie first: a slim caddis, a fuller hopper, or a golden stone?