Painting - Finishing a Cabinet top

I have an old corner kitchen cabinet which I have painted gloss black to use as a place for toy storage in a basement. The original cabinet was an upper cabinet so it had no top. Not wanting to make this a costly project since its going in a basement I opted not to use a higher grade wood for the top. I was going to simply use particle board & laminate on top of it but unfortunately the black laminate sheets at HD or Lowes were around $50 & they had no black high gloss sheets. I cut the particle board to size & painted it a high gloss to match the rest of the cabinet. Overall it looks OK especially for its intended use & location (Obviously I wouldn't want to use it in a fromal LR or Den, etc). My question is this - If I want to make the particle board top as smooth & shiny as possible what is the best way(s) to accomplish this? I've painted it & sanded it then repainted it. This seems to help but I wondering what else I could do - More sanding & painting? Staining it? Varnish? Tung Oil Finish? Clear Coat of something? Laquer? etc.. I understand that being particle board it may only look so good, nevertheless any ideas would be appreciated. Thanks

Try coating it with a good application of sanding sealer. (http://www.minwax.com/products/woodprep/lacquer-2.cfm) This will help fill the grain and provide a smoother finish.

A trick I have used on wood with inferior grain is to skim coat with drywall mud [or spackling] then sand almost all of it off then finish with 2 or more coats of paint. The small amount of mud left on the surface will fill in the irregularities making it look like a smoother surface.

Thanks for the info