T/D hybrid riser?

[Sigmazxcs]

Hi guys,
I'm thinking of making a T/D hybrid long bow, but I've not much idea on it's structural difference compared to a recurve or a longbow.

How different are risers in terms of form and length?
And how different are their limbs and the poundage they can handle?

Please contribute your inputs, I'd really appreciate it if you can help a budding (hopefully) bowyer!
God bless!