Hi Dilan, you can check Avinets https://www.avinet.com/en/mist-nets or https://www.avinet.com/en/mist-nets/ecotone. Most of the studies on bird netting mentioned or used this mist net brand. They have different net sizes and material you can choose that fits with your nesting requirements. 

Thank you very much Krizler & Hiba for your answers & support.

Mist netting is a very sensitive and very responsible area in the field of ornithology. In Sri Lanka training for mist netting is done by one or two professionals. Also remember malli you need a permit and permission tonet and  ring a bird from the DWC, which will only be issued once one has got enough experience working with a permitted bird ringer for a time period. Ringing carried out irresponsibly will effect the bird critically where most end up dead, or injured. Irresponsible ringing also effect there ecology very dramatically (recently we found that Blue Magpies near Sinharaja Reseach Station are no more there as they have left due to disturbance, many has died on the nets too as said by the local guides). Extracting a bird from the net needs high amount of experience and practice, the huge amount of stress caused at the moment could be lethal. One of the best bird ringers in Sri Lanka to my knowledge is Dr. Sampath Senevirathne, of the UOC. He is a Master Bird Bander trained Canada and has great experience and knowledge. Better consult him, he will guide you how to train to mist net and ring birds (they hold two training programs in Girithale and Bundala....try be be in them...). You cannot just hold up a mist net and capture birds...first of all it is illegal..It is a pleasure to see you trying to expand the scope of ornithological research further, in doing so do it in the best way with the best training.....Best of Luck 

Dear Moditha, Thank you very much for your answer and the valuable explanation. I appreciate it a lot. As you know I'm really interested in ornithological field. And also I like to learn and study about the avifauna of Sri Lanka. I agree with all your ideas that you have highlighted above and sad to hear about the present situation of Blue magpies in Singharaja. Specially I like to get a training that relate to mist netting even though I don't want to capture and ring birds. I will keep in mind the places that you have suggested for that. Thanks again for your answer.