Ade:
You can buy the stillages for far less than you can have them made, we were paying about £10 per stillage for ones big enough to take almost any Lister engine, all we did was to revise the bottom two cross-members so that they matched the bolt hole widths on the engines, then we just drilled holes and bolted the engines in.
The ones I have in mind were stackable as well.....
I've got some pictures somewhere, I'll have a look tonight.
The plastics and window industries use longer versions of these for transporting extrusions.
Peter