Well, this evening I got back to work on the on/off shutter for the pilot's side heater louvers. After measuring out a piece of scrap .025 thick aluminum, I cut and bent this puppy up.

By clamping it to the heater manifold, I traced one side of the slots to be cut. The other side of the slots were offset 7/16 from those.

Here are the 7/16 inch holes at the ends of each slot. Notice I couldn't drill the outboard-most slot since that slot wraps around the side. I actually thought about cutting these slots first, then bending the tab, but I really needed the tab bent in order to fit this into the heater manifold to trace the louvers. No big deal, really...it just took some careful filing to transition that particular slot over the bend and round the end of it.

Here's the finished product about three hours later.

Shown in the closed position. There will still be some air exiting two of the louvers, but since the louvers are bent out where you see the black, it'll be a pretty narrow slot for air to escape. Should be pretty effective.

...And shown here in the open position. Minimal coverage of the louvers in this position for nearly full air flow. Tomorrow's our EAA Chapter 9 meeting. The presentation's on a lift reserve indicator. I usually get home too late to do any work on the plane, so I'll have to pick this back up on Friday to do the sliding mechanism.