After looking all over the internet, I came to the conclusion that I wasn't happy with any of the train beds available. The only one I did like was super expensive. So I decided to make my own (I used a picture of the one I found on the internet to get approximate dimensions).
The bed is made out of 1/2 inch MDF, railing and trim is made with pine. All edges of bed are routered (except exterior edge of round part). I painted in latex paint and covered with acrylic satin gloss. Bed comes apart in several pieces...as all together it would weigh about 350 lbs and be unmoveable.
Major Tools needed:
3 - 4x8 1/2" MDF
4 - 1x4 Pine Boards
4 - 1.3 Pine Boards
6 Lag bolts
Step 1: Making Mattress Base:
Go buy a mattress and measure the dimensions. Then make the top part of the bed where the mattress will rest in. This is pretty simple to do. I used some L brackets for support on the inside corners of the bed. Used a brad nailer and glue to hold it together.
Step 2: Making the Round Part:
The diameter of the round part needs to be as wide as the top bed you made in step 1. Make sure you cut the circles out of the middle of the MDF (you will need the "scrap" piece to build the bumper of the train). I screwed together two pieces of MDF and then cut one cirlce to get exactly two cirlces the same size. You will then need to router out the inside edge of the circles to countersink the mason board you will use to wrap the round part. See See picture for how I put it together.