3' x 5' is still too small for a 3 lane ho track but you could try an oval .
2 lanes would be better. I did a two lane on a display table that is about that size and it is ok to run on but you won't get to full throttle. There is a build thread on here. Just search my posts/ threads. A few guys have put copper tape over the rails and it does work. I've done it.
Measure your plastic track for slot widths and rail distances. I recommend a good trim router for ho. I got a Ridgid model 2401. About $100. This will also work for the larger scales like 1/43 and 1/32
Good bits are a must!!!
Carbide steel at the least but I now use milling bits from a machinist supply store. 1/16" for ho is the size you want. (.062" ) I use Harvey Tools for bits. buy two, in case you break one. Nothing worst than having to wait to buy a replacement on a Sunday afternoon. You can google them. You may also need an adapter as the bits have a 1/8" shaft and most routers have a 1/4" collet.
4" is as small a radius corner you'll want, 5 or 6" is better. It will give a better flow to the track and the mega-g shoes wont hang up on them.
DON'T USE REBARE WIRE for your power rail. What a pain in the south side of a north facing slotter.
Flat or stiching wire is best, at least until you get some experience. Probably the hardest part is finding the right sized lock wire. The weed eater square ine is about the best solution we have found so far but you will need a different bit. A .085" bit works well for that.
Routed wood tracks are like Pringles, You can't eat just one.
Welcome to the wacky world of track building
Oh yeah. I used a chaulk board paint on several tracks now. It is an acrylic and has a little grit in it. I find that it does not matter what your tires are made of with it. All seem to work well.