Making the grating if done carefully is not hard.
Start with on piece of notched strip upside down with teeth up, and slowly add another to it with teeth facing down until the row is completed, then turn over and fill in the other rows with more strips.
To glue, I have found a bath in thinned out glue will hold most of the time, quick dip and set aside to drain and dry.
After the glue has dried a light sanding top and bottom to smooth things out.
Cut to shape normally in open area between ribs and then sand down to final shape needed.
Square ones are easy, the odd shaped used in bow are a bit harder, sometime making a paper or cardboard template first to use as cutting pattern helps.