Hey Finch,
My grills were made with what I had around plus some spray adhesive and grill cloth from Parts Express. I don't recall the adhesive's name, but it is one Parts Express recommends for grill cloth. It is a contact cement and works OK if you do not stretch the cloth TOO much. I stretched mine apparently a little too much and had to go back with bits of Gorilla super glue and temporary tape in places. I was disappointed in how the cloth was not true black, but got used to it, and it does seem to be relatively transparent. The grills soften things a tiny bit, but to me, not at all offensively, pretty evenly, and the imaging is still extremely good. It is the sound I have been working with though as I made the grills right after I got the speakers wanting a quieter look in my primary living space.
I cut the grills from some 3/8 plywood, and since you can see through the cloth, I spray-painted the fronts, sides and cut out interiors black (I didn't have much paint or would have painted the backs too), glued on the cloth on the back side only, and put on cut velcro pairs at the four corners of the backs of the grills. Then I removed the paper from the other side of the velcro adhesive and carefully adhered the grills to the speaker by pressing them on in the right position.
I got some grill pins, but wanted to use the velcro at first so that I could fully remove them (clean off the velcro adhesive) from the speaker if I did not like the sound of the grills. Turns out it works fine, so I have not put in the pins. I posted a couple pics.
I also got some spikes...the ones that Ziggy recommended fitting the speaker plinths, and I really like them on my floor and in my room. Madisound YSC1/4-20 spikes.
And finally, though I have made some bass traps and other room treatments, my room and speaker placement, my ears, my tastes, or a combination of the above cause me to prefer less bass than I was getting. I have a nearly all Decware system, a Torii MkIII, ZDAC-1, Mac Mini, ZSTAGE, Decware interconnects, Mac twisted silver interconnects, various after market power cables, and Decware speaker cables. Also a bunch of Herbie's Audio Lab stuff and vibration damping Dots from Marigo. I do love a textural clarified sound that is warm, but detailed listening to rock, but mostly acoustic music....simple jazz, bosa nova, single or a few instrument baroque, Irish traditional, minimalist choral music, but also the occasional bit of trip-hop and the like. Quite a lot of styles actually, but I have a sound that sounds like a live performance too me and this I love.
Anyway, with the Torii and the MGs I was getting too much bass, probably from my room arrangement. And I had done all the room treatment I could do while still looking more-or-less like a living room, so for that last percent, on Ziggy's suggestion, I experimented with the space between the plinth and the speaker bass. For me, the magic happened at about 1/4 inch as opposed to the original 3/8 inch spacers. The bass is still strong and palpable, but detailed. I love hearing the finger hits on a string bass string and still feeling the floor vibrate, so I am getting good bass.
Though this is my room and my tastes, I thought I would post this experience just in case anyone else can use it for their situation. The matching of aesthetics of a living area, and brilliant audio, for me has required a lot of learning and tuning. But I am happy. I have unbelievably real sound and it looks pretty low key. And since music is a primary component of our daily existence, for us it is important that it be in our kitchen/dining/living area. We also do not have an extra room, so there was no choice. And at this point I see no sacrifice...listening from the sweet seats is incredible with a deep, wide and articulate sound stage. The room pretty much disappears and the speakers look weird out there with no sound apparently coming from them! And for more passive listening, almost everywhere in the rooms sound awesome.
Will