After purchasing a Lumicon solar prominence filter I couldn't find an off-axis mask in time for an event.  So I went to the craft store and dug up a few things I thought might work.  I expect someday I may replace this, as it was a last minute creation, but so far it has worked quite well.

1. I purchased 2 large pieces of foam board.  The stuff used for presentations and such.  Cost - about $1.50 each.

2. The real trick is to figure out precisely how large to make the cutout so it fits snugly over your OTA end.  I experimented a bit to get the precise size.

3. The trick to get good results with foam board is to cut in 3 steps: first cut through the outside board.  Then cut through the foam.  Then finish the cut from the other side.  This way you get clean, precise cuts.  It is also critical to use a very sharp knife: the kind with snap off blades work great: after you make one or two cuts, snap off the end of the blade to expose a new edge.

4. In the above photo you can see I used a pin to make a hole for the compass.  Pushing the pin all the way through the board allows me to make the same exact circle on the other side of the board.

5. I cut out a number of these sections to get a good width with which to work.  If the foam board was 2 inches thick it would have saved this step.  Note below that I make a mark where they should stack, as to keep inconsistencies aligned.

6. Now I use a hot glue gun to glue them all together.  I then used 4 pieces of heavy duty Velcro with which to hold the mask portion.  I made this a two-piece mask so I could see what I was doing when putting the mask holder on first.  If I did it again I would eliminate this and simply glue the mask portion on directly.

(tip: this heavy duty Velcro is so strong I find it tears itself off its own adhesive when pulling it apart.  So I always add hot glue to it when applying it to anything)

7. Now using a same sized section of foam board I made the mask.  Again: the trick is to get the precise size for the Lumicon prefilter.  It's critical that the prefilter fit tightly inside the hole.  The last thing you want to happen is to have it fall out when viewing.  You'll also have to ensure the hole is midway between the primary edge and the secondary edge.

8. As is often typical with me, the filter was a last minute purchase for an upcoming event.  So the only used filter I could find was a 77mm prefilter.  This is too large for my 8" scope so I had to stop it down to around 58mm (2 1/4 inches or thereabout).  In retrospect I'm glad I got the larger prefilter, as I can always stop it down but if (when) I get a larger scope I'll have the right size prefilter.

9. In the above photo you can see I made a "bridge" to hold the stop ring.  At first I simply folded the stop ring over the prefilter but it wasn't a good fit.  Making a bridge like this also allows me to fine tune the position of the stop ring in case the prefilter hole is slightly misaligned.

10. This is the completed setup.

Overall I'm well pleased with this mask.  It's very light, very cheap (about $5 or so to make) and "programmable."

The day I got back from my event I had a message on my answering machine from Lumicon: "Mr. Lerch we now have an off-axis mask in stock for you."  Doh!