I am interested in building interior window panels for my house. I have a mix of double-hung and casement windows, dual pane. I can see the condensation line between the panels which means cold air is leaking past the seal on the double-hung windows, even when closed and latched.

I found Indow as a source of custom-made interior window panels, but I’m convinced this is an easy DIY job with significant cost savings, assuming I can source the materials.

The acrylic panel is easy: 1/8″ thick acrylic sheet is $3.62/ sqft ($4.34/sqft assuming 20% waste from cutting the panel to size)

I’m having trouble finding a source for the edge gasket material. It needs to have a 1/8″ channel to press the acrylic, plus a deformable edge that lets me press and hold each panel into place.

This is not something stocked at home improvement stores, and I’m having trouble searching through custom rubber suppliers to find the right profile.

Here is the description on the Indow edge gasket:

“The interior storm windows installed in the study home are Indow Windows—a single-pane, gasketed interior window insert. Indow Windows interior storm window inserts are made of sheets of acrylic glazing edged with a patented spring bulb made out of silicone and filled with urethane foam (Figure 2.2). The spring bulb holds the insert in place by expanding and pressing against the window frame. ”

Can anyone point me to a supplier that would sell me a roll of this stuff to cut to length myself?