Allotments 4 All

I have been thinking of making a raised alpine garden in my greenhouse and would like to know if anyone has any ideas on the problems of the weights incurred, and what kind of structure is best.    Please help.
                                                                                             

Eric's the expert?

Follow the links for some information. If you need any more please get back to me with specific questions.
http://www.allotments4all.co.uk/yabbse/index.php/topic,6751.0.html
http://www.allotments4all.co.uk/yabbse/index.php/topic,8533.0.html
Eric