Blending into dark colors is very difficult and generally shows; especially with high gloss finishes. It looks like you brushed or rolled the repair. Try airbrushing it to give a softer transition from repair to original.

It will most assuradly sand. Unless you are talking about destroying the texture of the stamped Masonite, which you will loose to a certain degree when sanding. Other than that, it will sand without destroying the panel. IMG_5477 (resized).JPGIMG_5464 (resized).JPG

Yes. The panels have a groove routed out for the bottom panel to sit in. The part that you're missing is the bottom portion of that channel. If you want it to match/blend in, cut thin strips of plywood and glue/brad it the the sides on the bottom. Here is a few pics of how I repaired some cab bottoms.
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This game was worse than the game in the previous pictures. After filling it in, I sanded it flush and filled the small gaps
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Everyone has their preference. I sand all mine off. Never had an issue with damaging a cabinet. I use 60-80 grit depending how it's cutting and change pads frequently. After a it's removed, sand the cab with 180, 220 and then 320 and it will be smooth. When head and then glue removal or sanding, it takes time. I hate messing with glue so I sand. Different strokes.

Taped hinge method. Lock the properly aligned first 8"-10" down and it will stay lined up. If the corners are bad, do as vid suggests and resin them. I just used this approach as I had a cabinet that warranted it and it's 100x's better than bondo.

You’re certain that same crack from the outside is all the way through to the inside? We’re asking the questions because it determines how to repair the problem. My guess is the veneer is split but the plys are intact. I could be wrong though.

I wouldn’t final sand primer with anything more course than 220. You’re not trying to remove any more material necessary than to level and flatten the texture of the primer. Seeing sanding scratches in primer showing through in finish paint is a bummer.

Yeah, I should have been more clear. What I was saying was I would never touch a cabinet for final sand with course grit that he list. I should have said I step from 220 to 320 to 400. It is glass smooth by then. Light, light pressure letting the paper do all the work.
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So true. A 2 part high solids urethane lays down so nice and sands and powders up even nicer. It’s well worth it.

Fiberglass resin.

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