Constructing a DIY Projector Screen Housing - Need Advice

Hi folks,

So I'm making a housing for a motorized home projector cinema screen. The idea is to suspend a 'bridge' between two Ikea Billy bookshelves. Two main reasons for this, the wall in my room is an old Georgian wall and I don't trust it to support the weight of the screen, and secondly aesthetics (it will be hidden in the design)

ATTN Mods: Not sure if this should be here or the woodcraft forum? I presumed here as there is more than just wood involved, but feel free to move!

I've drawn up some VERY rough digital designs to show you what I mean by a 'bridge'. I've knicked two images from the Ikea website to show you roughly what I'm getting at.

FRONT ON



As you can see in this image I currently have three ikea Billy bookcases in the room (one left, two right) with extension units on the top of them. The idea is two link the cases with two planks of wood, one at the rear of the units to mount the projector screen on, and one at the front of the units to disguise/hide the projector screen.

The projector screen is roughly 294cm across, and weighs 10kg. So the planks would have to be 300cm across to give a bit of space on either side to work with, and they would need to be 20cm high in order to hide the screen from viewing angle.

I've drawn a cut-away with a bit more detail on how I plan and attaching the planks to the unit.

DETAIL CUT-AWAY:



So you can see here (hopefully, apologies for the poor diagram!) that I plan on using two planks, one at the rear and one at the front, and the idea is to mount them using L-Brackets, four on each side.

And just for reference here are the dimensions on the motorized projection screen.

PROJECTOR SCREEN:



Weight: 10KG

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Okay, so now you've got the general gist of it.. I hope! :P The advice I need is really about the wood, and am I going about this the right way? My main concerns are that the Billy bookcases are made from what Ikea call 'particleboard', it's essentially chipboard I think, and I'm worried that mounting something this heavy into them won't work and it'll fall out. This would be bad, as all my AV equipment is underneath the screen!

So basically my main questions are...

• What type of wood should I use?
• Should I use 'L-Brackets' to mount them?
• Should I use screws to fit them or bolts/nuts/washers?
• Should I go for light weight wood?
• Will the 'particleboard' Billy Bookcases handle the weight?

Thanks in advance for any help! I'm a complete n00b when it comes to these kind of things.

Here's a few links to the items I've bought if you require more info.
Platinum 120" 16:9 Motorized Projector Screen
Ikea Billy Bookcase
Ikea Billy Height Extension Unit

-Adam