High vacuum chamber

Weldling; avoid dirt acumulation nooks and crannies, weld from inside full depth ( i.e. not both sides leading to trapped internal air pocket).

For sub 15µ powder use arm glove entry option port holes / non vacuum sand blast & suction clean up via filter (using metal powder not sand in blaster & Vacuum cleaner,

Special case of active metals i.e.Titanium, Nitrogen reduced oxygenated cleanup.

Use airlock for build while pump down contained in vacuum chamber door,

Further reading ; Vacuum chamber principles; Essential reading before you weld/construct your vacuum chamber, Basic Vacuum technology by Varian