An apparatus (100, 200, 400, 500) comprising: a radiation source (202, 402, 532); a processor (102, 204, 404, 502); and a memory (110, 212, 412, 510) on which is stored machine readable instructions (112-116, 512-524) to cause the processor (102, 204, 404, 502) to: identify (112, 514, 602, 704) an intended surface property level for a surface (208, 408) of a three-dimensional object (210, 410) through receipt of instructions from a user to fabricate the 3D object (210, 410) with the intended surface property level, or from instructions stored in a data store, wherein the surface property comprises at least one of roughness, texture, color, gloss, electrical conductivity, electrical resistivity, tribological properties or combinations thereof; access (520, 710) data identifying correlations between surface property levels and flash applied radiation amounts; determine (114, 604) an amount of radiation to be applied as a flash of radiation onto the surface (208, 408) to obtain the intended surface property level based upon the identified correlations in the accessed data; and control the radiation source (202, 402, 532) to flash apply the determined amount of radiation onto the surface (208, 408) of the 3D object (210, 410). a radiation source (202, 402, 532); a processor (102, 204, 404, 502); and a memory (110, 212, 412, 510) on which is stored machine readable instructions (112-116, 512-524) to cause the processor (102, 204, 404, 502) to: identify (112, 514, 602, 704) an intended surface property level for a surface (208, 408) of a three-dimensional object (210, 410) through receipt of instructions from a user to fabricate the 3D object (210, 410) with the intended surface property level, or from instructions stored in a data store, wherein the surface property comprises at least one of roughness, texture, color, gloss, electrical conductivity, electrical resistivity, tribological properties or combinations thereof; access (520, 710) data identifying correlations between surface property levels and flash applied radiation amounts; determine (114, 604) an amount of radiation to be applied as a flash of radiation onto the surface (208, 408) to obtain the intended surface property level based upon the identified correlations in the accessed data; and control the radiation source (202, 402, 532) to flash apply the determined amount of radiation onto the surface (208, 408) of the 3D object (210, 410). identify (112, 514, 602, 704) an intended surface property level for a surface (208, 408) of a three-dimensional object (210, 410) through receipt of instructions from a user to fabricate the 3D object (210, 410) with the intended surface property level, or from instructions stored in a data store, wherein the surface property comprises at least one of roughness, texture, color, gloss, electrical conductivity, electrical resistivity, tribological properties or combinations thereof; access (520, 710) data identifying correlations between surface property levels and flash applied radiation amounts; determine (114, 604) an amount of radiation to be applied as a flash of radiation onto the surface (208, 408) to obtain the intended surface property level based upon the identified correlations in the accessed data; and control the radiation source (202, 402, 532) to flash apply the determined amount of radiation onto the surface (208, 408) of the 3D object (210, 410).