My most dear, most kind, most precious, wish fulfilling one,
I am sorry it took many eons to reply to you. After checking, this is my advice to you.

You can do the practice by visualizing it and not doing the physical mandala offering. Do what you can. You don’t have to stay with 300,000 but keep doing the practice as much you can. Sometimes you can just do the short mandala but always with the visualization. The main thing is the visualization and the motivation. Your visualization doesn’t have to be complete, just as best you can.

Lama Tsongkhapa said in the Lamrim Chenmo that if you visualize one hundred bodies doing prostrations then you actually get that much merit. In the same way, it’s very important that you visualize the whole earth is covered by your body doing the mandala offering.

Similarly, regarding water bowls, to pretas it appears as molten metal, to worldly gods it appears as nectar, and to the buddhas it appears as most pure nectar and it tastes of nondual bliss and emptiness. The Buddha does not have even subtle obscurations, they are completely purified, so the Buddha does not have ordinary view or imprints. Everything appears pure.

What appears to the Buddha is most pure nectar, so whatever you offer to the Buddha, whose view is nondual with emptiness, you actually get that merit. It’s the same with the mandala offering.

The two most important things Lama Tsongkhapa focused on when explaining mandala offerings—he didn’t do much explanation but he just emphasized visualizing as many as possible and of the best quality. Lama Tsongkhapa only said that—to visualize many and the best quality! Regardless of the materials you have, visualize the best quality.

So don’t rush, don’t worry, don’t panic. Relax!

With much love and prayers ...

P.S. I gave a short commentary in Taiwan on mandala offerings. You may find it helpful to listen to those teachings.