I want to do a small hollow form and at the opening I was going to add three pieces about 3/4" ranging from about 3" at the base to 1-1/2 at the opening. The hollow form will be endgrain and I have two pieces of endgrain Blackwood. For contrast between the Blackwood I have holly or yellow heart, but these pieces would be side grain. Is it a "no-no" to mix endgrain and side grain?