What to use for fabric stiffener?

[SeS]

Hi, I'm new to MYOG.  My first attempt at a top tube bag came out okay, but would be better with stiffer side panels.  I thought something like 1/8" closed cell foam sandwiched between 2 layers of fabric would work, but I'm having trouble finding the right material.  What do you use, and where do you get it?  Do you have any related tips you can share?  Thanks.

[Adam Alphabet]

I've made a handful of top tube bags. While I don't really like using them that much anymore and don't like making them all that much anymore either as they're a lot of work for their worth I found making sleeves on the inside wall of the bag for .060 HDPE stiffeners to be very effective. I had an old Carousel Design Works TT bag and this is what Jeff used to do. Works great as it provided enough stiffness to open and close the bag with one hand while on the move.

[Racingguy04]

I found some flexible plastic cutting boards at the grocery store that were cheap and the perfect stiffness and weight for stiffening sides of bags. Sleeves would have been awesome if I'd thought about it when I was sewing the bag, but I just super glued them to the fabric.

[LittleOldLady]

I use a product called "soft and stable".  It is a foam product produced for the quilting/sewing market and is used in purses, bags, etc.  This stuff is exactly what it says, pliable but adds great stability to your bag.  Where I want structure I use a layer of X-pac, a layer of soft and stable, and an inside layer of coated nylon fabric.

[vermont]

http://www.michaels.com/creatology-foam-sheet-12x18/M10597609.html
I made a very small top tube bag with this stuff.  I also just sewed it into the fabric.

[marcsist]

Some art supply or plastics stores will have Polypropylene (PP) in a thin sheet. Old portfolio or art storage pouches are often made of it, as are those Asssavers fenders.

It's good and pliable but when properly encased can be quite stiff.

[SeS]

Wow, still getting replies!  (OP here.).  I tried to find the soft and stable, and also some thin polypropylene locally, and came up empty.  I ended up using some thin decorative foam, and it worked okay.  For the next project, I'll try to get something else as part of a larger order, so the shipping cost doesn't swamp the cost of the materials.  Thanks for taking the time to answer!

[Gudan]

Hi, I'm new to MYOG.  My first attempt at a top tube bag came out okay, but would be better with stiffer side panels.  I thought something like 1/8" closed cell foam sandwiched between 2 layers of fabric would work, but I'm having trouble finding the right material.  What do you use, and where do you get it?  Do you have any related tips you can share?  Thanks.

Use EVA foam. It is durable, does not absorb much water and keeps its shape. I'm talking to you as a bag manufacturer.