That dauxlite looks perfect. But if all you want to do is burn in while contact printing, why not just use a hole in a piece of cardboard like we did back in the caveman days. You could place a VC filter over the hole.......
In the 'old' days (post caveman days), I used to use a doctors opthalmascope\otoscope to selectively flash small areas of a print. They did not come with VC filters like the dauxlite, obviously, since they are medical insturments.
These units can be used to burn in areas when contact printing or to selectively 'flash' small areas when enlarging.
If some of you have never done any of the selective flashing, it can really help out areas of a print such as areas that contain highlight detail. I used the technique a lot on metal such as car bumpers out in the sun - it really helps improve the rich tonality of metal for instance - especially a small area that caught a lot of sunlight and is much brighter than other areas of the metal.
I believe I will get one of the dauxlite products. I'm tired of rubbing 2 sticks together to fix dinner and using cardboard with holes in it to burn in.
Here is a link to eBay showing a great picture of an odoscope:
The odoscope is a lot cheaper than the dauxlite but it does not have the VC filters so you would have to make some yourself. To cut down on the amount of light that it puts out, I used to stuff cotton in the attachment that goes over the light. The head of an odoscope has different size cones that control the diameter of the light beam that comes out. You could also just trim it back with a knife to make it wider. It is important that the light intensity be pretty low (depending on the speed of the paper) so that flashing\burning times can be long enough to control.
So, an economical alternatie to the dauxlite is the modified odoscope.
As for overall flashing of an entire sheet, like the RH Designs, I just placed a diffusion material (like diffusion glass or plastic from light boxes) under the lens of the enlarger (or over the top of the contact printer) and exposed the entire sheet. I would do test strips to find just the fight exposure to get just past the threshold of the paper and add in some base density. This will help out the highlight overall in the print.
Whatever you do, this selective flashing technique is a nice thing to learn and it can really help out some prints in just the right way.
BTW, like the overall flashing of paper prior to exposure, you can do the same think to film. You can pre-expose film to a low intensity uniform light source. This will serve to increase the films sensitivity to low light areas without significantly affecting it's sensitivity to highlight areas. In the caveman days, some of us would load sheet film hoders in dim moonlight to do this, then we would start rubbing 2 sticks together to fix dinner. Ah, the good old days.