Sealing doghouse holes

That metal foil tape you can get in the air conditioning isle at Home Depot or Lowe's works well but it's unsightly.

You might try a finishing plug, like these from McMaster-Carr:

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Welding.

Or beer cans. (Plus a little JB Weld.)

Sand both surfaces bright. Trim the patch to allow an overlap of 3/8" to 1/2". Draw a set of cross-hairs over/past the hole so you can center the patch. Apply a THIN coat of JB Weld. Press the patch in place, cover with waxed paper, apply a weight or other means of keeping things flat & in position.

Give it 24 hours to cure. 23 if you're in a hurry.

RTV will also work.

Or you can solder a patch in place. Use copper roof flashing or a piece of tin-can stock. Use eutectic solder and a 100W. iron (no torches please). If you keep the solder-line thin, use the nickle-based eutectic stuff (available from welding supply houses) and well-tinned THIN steel for the patch, this method works almost as good as welding.

Fiberglas will also work. Use epoxy resin rather than vinylester. Score the steel with a #24 flapper... the resin needs some 'tooth' to get a grip on. Saturate the patch atop a piece of Saran wrap. Provide some means to press/hold the patch in place until it cures. Leave the Saran wrap ON the patch until it cures. This type of patch will come off after a while.

For a temporary patch of a small hole, JB Weld & beer can aluminum works best.

The proper fix is to weld or braze the hole closed.

BIG hole (air conditioner compressor cut-out, etc), semi-permanent patch, rivet the patch-plate in place. Make the patch-plate out of aluminum roof flashing. Use RTV as a sealant; overlap about 3/4". Accurately size the patch, do several trial fits, then drill the edge of the patch for a pop-rivet about every inch. Drill the first hole then hold it in place with #6 sheet metal screws as you drill the others. Then remove the patch-panel, debur the holes, apply sealant, put the patch in place & hold with a few screws while you do the poppers.

This is also the Po' Boy Muffler Repair. Use tin-can stock instead of aluminum, high temp RTV instead of regular. Usually holds up just long enough to pass smog. (If for a fuel tank, use polysulfide sealant [get a tube of it from a boat shop] and use closed-end poppers, dipped in the sealant before being inserted in the hole.)

Few thousand other ways to do it but I haven't had my coffee yet...

-Bob Hoover

For holes on a black surface, I usually use Permatex black rtv sealant gasket maker. I am not sure of the name but it is not the wheather stripping adhesive made by the same company. Clean the surface first with some rubbing alcohol on a clean paper towel, let dry, and neatly dab a little of this goop in the hole. Let dry a few hours or overnight. It also works well for small holes in the trunk area up front to help keep a freezing breeze from entering the cabin in Winter.

Rubber plugs that have a groove cut into the side.

Or maybe you are talking about the holes for the plug lead holders?

Jan