Not quite sure I understand what a window insert for sound dampening is? Can you find a picture?
It sounds like something that fits tight into a window frame, that is made of sound absorbing material to reduce sound coming through the window from outside, or is it to reduce sound inside, so it doesn't echo off the window.
If the later, you should be able to use something pretty simple. Fit the sheet fairly tight to the window frame, then add a layer of dense foam around the edges so it makes a tight friction seal. I know you can buy acustic foam that has diamond shaped points to absorb sound, but that can just be glued in place with spray on contact cement, or even double stick tape.
Acustic foam comes in squares for the most part, and it seems to me that simply extending it slightly wider than the window measurements would form a tight seal without having to fiddle with a separate edge treatment. You could add two small handles for easy placement and removal.
Long ago had a friend with a studio in his garage who just used acoustical tiles for his studio, but he lived on a quiet street so ambient noise wasn't a big deal. If appearance is an issue, you could always cover it with some coarse woven cloth or even burlap.
Found 24 sqft of 12x12x2 inch acoustic foam for $40 on Amazon. https://www.amazon.com/Acoustic-Sou...42MiIsInFzcCI6IjYuMjEifQ==&sr=8-2-spons&psc=1
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It sounds like something that fits tight into a window frame, that is made of sound absorbing material to reduce sound coming through the window from outside, or is it to reduce sound inside, so it doesn't echo off the window.
If the later, you should be able to use something pretty simple. Fit the sheet fairly tight to the window frame, then add a layer of dense foam around the edges so it makes a tight friction seal. I know you can buy acustic foam that has diamond shaped points to absorb sound, but that can just be glued in place with spray on contact cement, or even double stick tape.
Acustic foam comes in squares for the most part, and it seems to me that simply extending it slightly wider than the window measurements would form a tight seal without having to fiddle with a separate edge treatment. You could add two small handles for easy placement and removal.
Long ago had a friend with a studio in his garage who just used acoustical tiles for his studio, but he lived on a quiet street so ambient noise wasn't a big deal. If appearance is an issue, you could always cover it with some coarse woven cloth or even burlap.
Found 24 sqft of 12x12x2 inch acoustic foam for $40 on Amazon. https://www.amazon.com/Acoustic-Sou...42MiIsInFzcCI6IjYuMjEifQ==&sr=8-2-spons&psc=1
