Astrozap dew shield

[inapottingshed]

The postman (really DHL person) brought an Astrozap dew shield sans cutouts. It won't fit over my top ADM rail (guide scope), which is 2 1/2" wide, or my bottom ADM rail (Losmandy dovetail) which is 4" wide. Someone told me that the Astrozap shield with cutouts has top and bottom cutouts that measure 3" wide (which is still not wide enough for the bottom rail). Can anyone confirm please?  

[inapottingshed]

Rather than send it back I've taken a Stanley knife to it and now have a dew shield that fits snugly around the top and bottom rail. Briefly, I used paper masking tape aligned to the edges of the rail to determine the cut line. Measured depth with an engineer's rule and set to cut. The outer skin is quite tough so definitely need to watch fingers when cutting. I found it better to press the knife down rather than slide (making sure the blade is locked). Once through the outer skin the foam backing cuts easily. As always, for such operations, measure at least twice and cut once. I did the top cutout first, fitted the shield, then used the tape method for the bottom rail.  

[tomato]

I did the same job on a Celestron flexible dewshield for my RASA 8 to clear the wider dovetail. Where I cut through the layers I just put a couple of staples in to stabilise it. Sound advice about making sure you know where to cut.