Lovely detailing on this cake. It would be fairly time consuming but would be great fun. I can make something like this for if you provide the characters or I could do some of the Lego characters in sugarpaste for each.
I could do this as for 2 tier or for single tier but would need you to provide the Lego bit for the topper. I can add characters for each or you could provide them. I would put the cake on a larger board and have Happy Birthday etc written on t