Alpha One designed the first blocking field generator shortly after the Lights had invented their light circuitry. The universe was still young and filled with extreme amounts of radiation with much of the matter yet to condense into stars or planets. That meant that the Lights lattice bodies needed to be repaired quite often by the early version of threads, causing their lattices to become lumpy and very massive. He decided h was tired of needing to rebuild and reshape his lattice every few million years and decided to find a way to prevent the damage.
The first blocking fields were nothing more than extremely powerful magnetic field generators which deflected the matter which caused most of the damage. After the Lights discovered that each dimension in the universe had its own special field permeating it, Alpha One discovered a way to manipulate the fields in order to create a multi dimensional well around an object. Depending on which fields were manipulated and how strongly, anything could be blocked from passing through.
After the Great Misunderstanding, Alpha One designed a total blocking field which he believed could completely cut off one area of space from everything else. He did not know at the time that a total blocking would cause tears in the fields which were being manipulated.