I haven't seen anything that even looks like mauls on any custom site...
TCSS MHS Bladeholder #6 "even looks like" Mauls...unless you mean you want one EXACTLY like Mauls in which case you probably wont find one "on any custom site" because that wouldn't be a custom
part that would be a REPLICA part.
Replica sabers and custom sabers are not the same thing...because smiths can make any number of custom parts they choose, but replicas are another matter entirely. Unca George OWNS the copyrighted designs of lightsabers used in the movies [and even the trademarked word "lightsaber" which is why sites are fx-sabers/the custom saber shop not fx-lightsaber/the custom lightsaber shop eh?] and therefore owns the design of all their major distinguishable parts [except perhaps
for OT hilts which were made from preexisting camera flashes and other real-world parts] so smiths and shops can't just make as many replica parts as they want and 'stock' them on a regular-available basis.
Afterall Hasbro pays Unca George MILLION$ for the EXCLUSIVE right to make replicas so Unca George is contractually oblicated to protect that by defending his intellectual property...If smiths or TCSS made regular production of bladeholders that looked EXACTLY like Mauls the 'heavy-paper' turbolasers of Unca Georges army of legal-stormtroopers would soon embroil them in 'imperial entanglements' and soon there would be no CUSTOM parts for anyone...everybody loses.
So you wont likely see Maul replica emitters from custom smiths unless someone does a small run that flies 'under the radar' because it is too few to be a threat to Hasbro/LFL licensing and not worth the Empire crushing...or you get some smith to make a one/two-off for you which considering the complexity of that part(s) and the amount of time and math necessary to set up tooling or CNC for would probably cost you more than a whole Maul FX...you would probably be better to just stick with one of those and get a custom pc/paintjob if a Maul-ish BH #6 isnt close enough for your liking.
edit: Luminara beat me to it...I hate being a slow typist lol