Cutting a hatch in a PE deck neatly

[chuck]

I am building a Uboat model using a PE deck. I like to open up the torpedo loading hatch to show the boat in the process of striking down a torpedo. This requires a flush door on the deck over the hatch to be opened. On the PE deck the flush door is demarcated as a scribed line on the PE. Normally if I need to cut a hole out of piece of brass I will drill a pilot hole through the middle of the hole first, and then use a sharp cutter like a scissor to cut out the hole. But that usually leave a down turned edge around the hole, and destroy the piece that is cut out to make the hole. I need to save the door in the middle and not destroy it, while make the edge of the cut as smooth and flat as possible.

Is there any tool or special technique that can cut the door cleanly out of the PE without living any down or up turned edges while saving the piece to be cut out?

[Admhawk]

Laser cutter if you know anybody who has one.

[chuck]

Unfortunately I don�t

[Pieter]

If the door has straight edges use a steel ruler and score repeatedly with as sharp, new, blade on a hard surface. I use a piece of glass if I need to do this. After this the PE will be bent upward a little. A plier can flatten it again and you can remove any little edges of PE still in the hole with a small folded piece of sandpaper. Practice first on a piece of PE 'sprue'. PE sprue is useful anyway if you want to build anything under your torpedo hatch.

[spejic]

If you are using a sharp tipped blade on a hard surface, be sure to wear eye protection.

I learned that the hard way.