Have just cut out a Mollegabat from an ash board and have two pieces left that I was thinking of making bows for my kids from. They are 1.5"X48" and 2"x48", my kids are aged 5 & 7. Looking to make them something in the 18-20# range. Would these 2 pieces be suitable and can anyone give me some dimensions please?

i did a 48" kids bow for a buddy of mines boy. it was a 1/4 inch slat. i glued on an 8" riser and tapered it just a hair into the slat so that the riser wouldn't pop off. it was about 1 3/4" at fades and straight tapered to just under 1/2" tips. i backed with brown paper, camo painted, cut the shelf to center, and put in a greatly reduced locator grip, that i wrapped in bailing twine and TBIII. i was shooting for about 10-12 lbs for a 5 yr old. if you want 20 lbs, you can always add a thin backing strip, which will bring up the weight. tiller from the side when you start making bows that thin.
don't forget that backing is a safety factor, for the abuse a kid is sure to inflict on a bow...even he treats it right, one of his friends is sure to pick it up and over draw it.

Great, thanks very much for the advice, have some linen left over from the Mollegabat so i'll use that to back it.