What is their current size and I was once told future modernization plans include doubling its size.
50,000 to 60,000 and It will get bumped by another 15,000 by 2025
BGB has adopted a long term modernization plan named "BGB Goal 2041" in 2017. The plan intends to make BGB a well-trained, well-equipped and technologically advanced force.
In short terms, BGB plans for structural and manpower expansion. A new region (equivalent to division) will be raised in Ramu of Cox's Bazar. Three new sectors (equivalent to brigade) will be raised at Ali Kadam of Bandarban, Naogaon and Jessore. Eight new battalions will be formed at Jhikargacha of Jessore, Meherpur, Khagrachari, Boro Mowdok of Bandarban, Gazipur, Narayanganj and Kulaura.
Two riverine battalions will be raised in BGB at Nildumur of Shatkhira and Teknaf of Cox's Bazar. They are the first two units of BGB who will be able to operate in riverine borders and chars (River island). The number of personnel will be increased from 50000 to 65000 soon. 124 Border Out Posts (BOP) and 70 heli-support BOPs are being set up in the border areas of hilly districts along the border with Myanmar. 128 Border Sentri Posts (BSP) are being constructed between the distant BOPs. BGB members ae being equipped with bulletproof vests and ballistic helmet.
A Quick Response Force will be established for BGB. The force will work to supply modern arms and ammunition swiftly to border points in case of any emergency. For smooth operation in the border areas, border roads are being constructed. In BGB day 2017, prime minister said that the government has undertaken a plan to construct a total of 3,167 km ring road across the borders with India and Myanmar.
BGB intends to go three dimensional as per the plan. Bangladesh government has already approved the proposal for buying two Mi-171E helicopters from Russia at a cost of Tk. 355.10 crore. However, Bangladesh Air Force pilots will fly the helicopters initially. A heliport with hangar is being set up at Baitul Izzat in Chittagong. Eventually, BGB plans to have four aviation wings.
To effectively monitor the border, BGB plans to add modern technology to the border management. The plan is to set up cameras, night vision goggles and infrared sensors throughout the border. BGB plans to achieve 3I (Information, Identification, Intervention) capabilities in the border in long term. Having Radar and Satellite monitoring facilities in the border are also planned.
https://en.wikipedia.org/wiki/Border_Guards_Bangladesh#Future_modernization_programme