Joey wrote:

Hi guys, I'm not a member of this group and this is my first post.
Forgive me if I've posted incorrectly.

I have a question that I hope someone can help me with. I am restoring
an old pinball machine and I need to refinish the plywood cabinet. It
has a slightly rough texture with some very fine cracks in it. I've
been able to sand it smooth while prepping it for latex painting, but
the tiny cracks are still there. There are purely cosmetic minor
cracks in the wood and it is not delaminating or loose. I need some
way to fill them so that when I paint the cabinet, it will look as
slick and smooth as it did when it came from the factory.

I have been looking at the following options:
1. Paint on an epoxy sealer. Allow it to fill the cracks and bind for
two days. Sand smooth.
OR
2. Find a thick primer (automotive high build primer?) that I can
paint on that will fill the cracks. Allow it to dry. Sand smooth.

Is there another easier option?
I've been consulting with someone who does wood boat refinishing and
he says I need to do both 1 AND 2! I think that's overkill since the
pinball machine doesn't need to be water tight and I don't plan to try
to float it in a lake.
Any advice would be great. I really just need to fill in these very
minor cracks to make the cabinet look smooth. Wood fillers or putties
are not an option because the cracks are very very shallow. Possibly
half a mm. Plus, they run about 3-4 feet long in some cases. I need an
easier paint on method.

You need a polyester fine surface filler. This you will apply with a
semi-rigid spreader
which will push it into the cracks, and also make it more easy to
control the thickness of the coat. It will also set ready for sanding
in around 30 minutes. Don't buy the wood finishing
type; buy the vehicle finishing type which are just the same but only
half the price. A 4 inch spreader is probably the most comfortable
size for the job.
HTH