I've been looking at my 1/2 finished baseboards every day when I pass through the garage. Today I threw caution to the wind and actually finished them. I had previously glued the endplates on and made sure that they were in the right places etc. I only had to cut the sideplates out and glue them in. This is the part that I had dreaded, as I would have to fire up the sawbench. I marked out the sideplates and then cut them to size (and all correct first time !). I tacked them in place and then ran PVA around all the joints on the inside. And the result? well, My old woodwork teacher would not be impressed ('thats a nice set of shelves lad, pity we were making a footstool').
Well, its serviceable, and is 6' by 1' (about 12' by 2' in the next scale up ).
I'm wondering if I should move to plywood, as MDF doesn't really like tacks. The other option is to return to the Cass layouts inverse L-girder style, which would be made in pine, but would be much easier to cut out. I'm almost tempted to revisit this, as it served me well in the past.