Hey @russellg, 
I was able to read and write a PDF file as follows:
Created a request fetching a PDF file:
In the “Test” script I’m sending the raw response stream to a locally running server.
localhost/save is the endpoint of the server that I’m running.
pm.response.stream is the data I sent to this server.
I’m running a PHP script at the local server to read the data and write it to a file.
This is how my server-side PHP script looks like
<?php
$FP = fopen('./saved.pdf','w+') or die("Error creating PDF");
$outp = fopen('php://input', 'r+') or die("Error reading data");
// pm.response.stream is a JSON object so we decode it first
$json = json_decode(stream_get_contents($outp));
// PDF data is inside the 'data' field
// All bytes are stored as an integer
$data = $json->data;
for($idx = 0; $idx < count($data); ++$idx) {
// covert the bytes to characters (binary) and write to the file
fwrite($FP,chr($data[$idx])) or die("Error writing data");
}
fclose($outp);
fclose($FP);
echo "Written!";
I was successfully able to open the saved.pdf file.
You will have to see how this can be done in the language of your choice!
Hope this helps 