Need some help with my latest piece..

I would use plastic cement and glue an acrylic tray together, or buy one of a suitable size then fill it with a layer of water-clear casting resin.

Once/while the resin cures you can carefully position the condoms and then add another layer or two of clear cast resin until covered.

If your walls allow drill 6 counter sunk hole around the edge of the acrlic then screw into a white back board, with appropriate fixing attached to hang.

Done...