Buy a silver briefcase style camera case. You can get them all over the place for not a lot of dough.
Inside the width is usually around 16 inches.
Go to your local hardware/timber yard and buy a few lengths of decking timber.
Cut them (or maybe the timberyard will cut them for you) so that they fit inside the camera case.
Lay 3 of them alongside each other and then put a couple of short ones underneath and then cut them to size. Something like this small board i made (i made the pedals too

):
Then just use a couple of nails woodscrews to hold it all together and add velcro.
This bigger board has two layers and fits snugly inside a camera case. You can see how easy it is to stack up pieces of decking to customize the board to fit what you need:
You can see how neatly the patch leads sit underneath the boards (ala pedaltrain). This board also has a dunlop power brick tucked away underneath too.
That one fitted two double width pedals and a wah. Usually you need to budget 10cm (4 inches) per pedal if you are going to use chunky right angle plugs so with this style of board you should be able to fit at least 4 pedals across the board, but of course you can always stack it up and make a second higher tier if you want to fit maybe 8 boss pedals (or maybe 6 plus a wah).
If you want a small power supply, the pedaltrain volto will fit underneath even the small board in the first pic if you buy some rubber feet for the board.
The other great thing about these is that you know they are strong enough to stand on...they are decking boards after all! And of course once you sand them down smooth you can paint them in whatever colour you like.