Ton,
In the Houston area you have several choices. First is to rent a compressor and blasting pot from a tool rental place. There is one on the west side and another on old katy road that have a rig I have used. You can use sand on anything but your flat sheet metal sections. I would recommend using a DA to sand the panels instead of blasting. The frame can be blasted using sand which is available from Sears Harware stores or some building supplies like MCCauleys in Tomball.
There are also two shops in the area that do this type of work. Houston Metal Strippers up north in the Woodlands area can blast or dip your whole rig or if you are down south there is a sand blasting outfit in Pearland that some have used. I can get you the contact there if that is your area.
You can also do it yourself with a simple siphon blaster and a bucket of sand if your compressor is up to the task. I clean many a part and some panels that way. The pressure does not get high enough to damage even the flatest panel.
