any one know how the home made bamboo rocketd are made for the Thai new year?

The rocket festivals have evolved from pre-Buddhist fertility rites held to celebrate and encourage the coming of the rains.

Today, they are mostly held in Laos and in the Thai provinces of Yasothon and Nong Khai.

According to Wik,

Bang Fai are made from bamboo bongs. Most contemporary ones, however, are enclosed in pvc piping, making them less dangerous by standardizing their sizes and black powder charges (which contest rules require be compounded by the rocketeers, themselves). Baking or boiling a bong kills insect eggs that otherwise hatch in dead bamboo and eat it, inside out. Skipping this step may cause the bong to disintegrate and melt the pvc piping. Vines tie long bamboo tails to launching racks. The time it takes for the exhaust to burn through the vines (usually) allows a motor to build up to full thrust; then the tails impart in-flight stability. Ignition comes from a burning fuse or electric match.

I'm not a rocketeer or a rocket scientist, but ..

The renowned scholar, William Klausner, who has studied Thai culture for more than 40 years, has made these comments on the origin of the Bun Bang Fai festival:

…it incorporates Brahmanic, animist, and Buddhist elements. The festival usually occurs between May 15 and June 15. As might be expected from the time of year, the festival is concerned with assuring abundant rains.

In Laos, the Bun Bang Fai ceremony is intimately associated with Buddhism as the ceremony is held on the same day as Visakha Puja, the ceremony commemorating the anniversary of the birth, enlightenment, and death of the Buddha.

What is important to understand is that – before the festivals became somewhat commercialized – Bun Bang Fai ceremonies played an important role in village life as a purgatory “ceremony” where many repressed feelings can be released in a socially acceptable manner. Bun Bang Fai ceremonies were essential to the psychological well-being of the villagers (who in day-to-day dealings of a self sufficient economy all were inter-dependent) and to the social order, stability, and solidarity of the village.

You may be misunderstanding about bamboo rocket is not make for Thai New Year in the north-east part of Thailand.

The bamboo rocket ceremony held for raining from Thai Deity and it will be held in the 6th month.