At most local contest we use the trust the flyer to tell us the weight and look at the plane. At the National Contest they use a digital gram scale set to 5kg or a balance the plane with a 5 kg certified weight.

For myself I use a fishing scale to get the ball park and go to the UPS store or the Post Office. My pattern flyers have their own digital gram scale. The worry at a 2 gram difference in the wing masses.